... as perceived by a long-time SWTOR fan who had never played KOTOR until recently. Does that title still sound click-baity enough?
To get the obvious out of the way first: KOTOR and SWTOR belong to two different genres: single-player RPG vs. MMO, so of course they are going to be different in that respect. However, the single-player part of SWTOR has been labelled as basically being KOTOR 3 by both players and devs (I think Bioware even called it "KOTOR 3-10" once, because of the eight different class stories), so it only seems fair to take a closer look at that comparison.
1. Combat / Controls
My very first post about playing KOTOR on my tablet contained a lot of whinging about the controls. Just moving around was a pain, inventory management was a nightmare and so on and so forth, though I'm not always sure how much of that was the fault of the mobile port and how much can be traced back to the base game. I do feel confident in saying that the combat plays out very differently than in SWTOR though.
SWTOR is based on "classic" MMO tab-targeting combat and while that's not everyone's cup of tea (it does seem to be going out of fashion as of late), it's tried and true for a reason. While I think that the massive, game-wide nerfs applied in 4.0 have diminished the fun of combat somewhat because things die too quickly now, the general concept of having lots of different buttons to press in different situations is fun.
KOTOR on the other hand works with a sort of hybrid turn-based, real-time combat system, which is to say that you can just let it run or pause at any time to give new instructions to your character and your companions. I suppose your mileage may vary in terms of which combat style you prefer, but personally I thought that the combat was definitely KOTOR's weak point, mainly because it's just strategic enough that you can't simply let it proceed in real-time, but way too simplistic to make planning your turns any fun. For example there is no restricting factor like "energy" for non-Force special attacks, so there is basically no reason to ever use an auto-attack... but for some reason all your characters will want to perform them by default all the time, so most of your combat management is spent cancelling auto-attacks and forcing your party to perform specials instead, which is just tedious.
2. Different Freedoms
In general, whenever I see people complain that SWTOR isn't enough like KOTOR, their main issue seems to be that SWTOR is too restrictive and they feel like their choices don't really matter. Based on that, I half-expected KOTOR to be a wildly open game... but it wasn't. In fact, there was still a very strong plot thread that you have to follow and which I'm confident you can't deviate from, even after only having experienced one playthrough. You always start off by having to rescue Bastila Shan (which you can only do by winning that swoop race), Taris always gets destroyed, then you have to train to be a Jedi, then you have to hunt down the different pieces of the star map and so on and so forth.
What KOTOR does do better is granularity of choice when it comes to how you want to achieve certain things. I thought the Sith Academy on Korriban was a great example. You have to impress the head of the academy to get to the tomb with the star map, but there are a multitude of options to gain favour with him and you can pick and choose the ones that would suit your character best. Inside a single conversation there are often also several different options for what to say: do you want to try to be persuasive, intimidating, reasonable? SWTOR limited itself in that regard from the start by adopting a conversation UI that doesn't allow for more than three conversation choices at a time. When SWTOR gives you a choice of how to tackle a certain situation, it simply comes down to doing the nice thing or the evil thing most of the time, with no in-between.
From a mechanics point of view, KOTOR also allows for greater character customisation as you go along, what with the different skills, feats and powers you can invest into opening up a huge amount of possible permutations.
However, I dare say that KOTOR doesn't give you more freedom across the board. For example, it doesn't really matter what class you pick at the beginning, the story quickly turns you into a Force user. I suspect that for many this doesn't really matter because a Jedi/Sith is all they really want to be, but for me, one of the big appeals of SWTOR was that it wasn't "just another Jedi game". While the recent expansions have somewhat gone back on that promise of an experience tailored to different roles, at least the base game genuinely lets you experience life in the Star Wars universe as a trooper, smuggler, agent or bounty hunter. Or a Jedi/Sith, if that's what you want - but it's not the only option.
Also, in terms of geography, SWTOR offers so much more real estate to uncover and play around in. All the planets in KOTOR are pretty tiny and I don't remember single area that wasn't obviously just placed there for quest purposes. I found this particularly striking on Tatooine, which is absolutely vast in SWTOR, but encompasses only a tiny couple of areas in KOTOR.
I've almost always been against the kind of thing that certain critics describe as the "dumbing down" of MMOs, but playing KOTOR really gave me a new perspective on this because parts of it are just too damn opaque for my liking.
I suppose you could say that KOTOR is more true to the roleplaying roots of the genre in the sense that it's less gamified and there's more "real world logic" going on. As an example, there are no "trash drops" from mobs like rakghouls or kath hounds, because realistically, nobody would want to buy stuff like broken rakghoul teeth. On the other hand, if you kill a Dark Jedi, you generally get to loot his lightsaber and gear. SWTOR leans much more strongly on modern MMO conventions here, where you can farm anything for money but you can't usually count on getting anything exciting from it.
Now, the above didn't actually bother me, but there were other things in this category that did. When SWTOR launched for example, I remember them making a big deal out of the fact that you would not be at a disadvantage based on whether you made light or dark side decisions. I didn't quite understand why that was even a concern, but KOTOR quickly made me see why: If you go down the light side path in KOTOR, you get royally screwed over in terms of money, which can turn certain points in the story where you are supposed to pay x amount of credits to proceed into real roadblocks. Meanwhile, dark side characters are free to rob, steal and extort every step of the way and it pays off. I even found guides that recommended that you always go dark side of the start of the game, regardless of your plans for your later alignment, just because it's too much of a pain to progress during those early levels otherwise. Now, that may well be "realistic" but doesn't make for a fun experience when I'm playing the game to live out my fantasy of being a goodie two-shoes Jedi.
Likewise, while I found the combat itself pretty tedious, the underlying stat system is reasonably complex. There are several different types of damage types and resistances for example, based on the Star Wars d20 tabletop game as far as I'm aware. The problem is, without having read the rulebook for that, how it all works is frustratingly opaque. I remember getting a piece of armour that said it had x amount of resistance against frost. But what exactly does that mean? That I have an x% chance of resisting a frost attack? That I always resist x frost damage each round? How many opponents even do frost damage? How do I know how useful this is? To this day I'm not sure why certain pieces of gear suddenly made my Force powers unavailable. "Restricted by armour" is a frustratingly vague explanation. Was there a manual supposed to come with the game that explained all of this?
This is all taken to eleven by the character builder. As mentioned above, the fact that it gives you lots of choices can well be seen as a positive, but you can also make a lot of "bad" choices here, and you won't necessarily know how bad they are until it is too late. The prime example of this was my frustration with the final boss fight - I had built my character largely around stunning, healing and support, which worked just fine as long as I had my two companions with me, and even when I went up against that duo of terentateks on Korriban while on my own. But then I was thrown into the final fight where I suddenly would have needed a Force attack power - which I didn't have, with the result that the final fight was, while not completely impossible, incredibly hard, long and tedious. It was bad enough that I honestly considered quitting the game there, even though I had come that far already. Putting the player into that kind of position - a situation which is completely different from anything that came before and where all their choices up to that point can suddenly turn around and bite them in the butt - is very bad design in my opinion.
TL;DR: While SWTOR may well have taken streamlining a bit too far for my liking in some areas, personally I appreciate that it makes it impossible to ever end up with a character that is too seriously disadvantaged to progress. The biggest thing that you can do wrong in SWTOR is press the wrong buttons for the situation - but that is something that is easy to correct at any time. Also, while some might be annoyed by the fact that you can't reject or kill companions early on, you also can't lock yourself out of a companion story by accident - I didn't complete a single companion's arc in KOTOR largely because that is possible in that game.
While both KOTOR and SWTOR are set in "the Old Republic era", SWTOR takes place about three hundred years later and has a somewhat different feel to it in some respects. For example I explained in this post how the Sith Empire comes across both as a bit more reasonable but also somewhat less interesting in KOTOR than in SWTOR - I would say it's a matter of taste which portrayal you prefer, as both have their pros and cons. The Republic doesn't really get much screen time in KOTOR other than to show up for space battles - if you are interested in how things were run during that area, SWTOR offers a great opportunity to explore important Republic planets like Coruscant and Corellia to get a feel for what things were like there.
Side missions in both games also follow slightly different formats. I've seen SWTOR get accused of "having too many boring fetch quests" compared to KOTOR, but this comparison strikes me as unfair as none of the side missions in KOTOR are really very deep either. The main difference to me seemed to be that the KOTOR side quests almost always relied on some mystery: "Where is X?" However, this wouldn't have worked for SWTOR since people are used to modern MMOs telling them exactly where to go. The Search for Shasa would have been a lot less intriguing if the moment you picked it up a map marker had told you exactly where to look. Instead SWTOR mostly opts for missions where the quest giver knows at least roughly where to go but can't do the job themselves because the environment is too hostile or whatever. Ultimately however I didn't feel that this made the two types of side quests feel all that different - they still have little to no connection to the main plot and mostly serve to give you an idea of what else is going on on any given planet.
In terms of overall writing, it seems to me that SWTOR is a worthy successor to KOTOR. I enjoyed playing through the latter even more than a decade after its release and with the main plot twist having been spoiled for me. It hits many notes that are "typically Star Wars" while occasionally veering into slightly clichéd territory, though that doesn't detract from the overall enjoyment too much. If you want a similar experience in SWTOR, you can get this either via the Jedi knight or the Sith warrior story - depending on whether you want to be a good or a bad guy. You just have to make up your mind about which side of the fence you want to be on from the beginning - while you can be an evil Jedi, you'll still remain a Jedi regardless and can't suddenly go join the Sith. KOTOR could (presumably) afford to let you go off to rule the Sith at the end if you wanted to, but only because that was the end of the game and they didn't have to worry about showing you what comes after. SWTOR is a continuously ongoing story, so there are certain limitations to how far they can let you veer off the main story rails. But as long as you go into that with eyes wide open, there is no reason you can't enjoy SWTOR's story as much as the original KOTOR (assuming that none of the gameplay differences mentioned above are absolute deal-breakers for you).