I remember when I first started PvPing in SWTOR, I always used cardinal directions when making calls, e.g. "2 east". But it didn't feel like I was having much success with it, and everyone else seemed to prefer calling things by some different designation. I eventually decided to go with the flow and adjust my calling habits, but I still don't know what SWTOR players have against the compass.
First there is the aforementioned Alderaan Civil War with its grass and snow sides. To this day, I don't like this way of telling the sides apart, for two reasons. Firstly, there is snow on both sides. One has less, but if you don't know the look of both sides very well, it can be confusing. Second: If you're in the middle, you can't actually see which side is which without running very close to the side to peek over the edge - and if you happen to choose the wrong side because you can't remember whether grass is east or west, you just wasted a lot of time while trying to come to your team mates' aid.
Huttball is, thankfully, mostly free of directional calls, since there is only one objective and its position is always highlighted by a giant pillar of light. People might say "up" to encourage someone to pass upwards, or "wrong way" if someone gets turned around and tries to carry the ball back to their own goal line, but those are fairly unambiguous.
Voidstar, the last of the original three warzones, is another fairly confusing one. This one even explicitly refers to the door objectives as east and west (or north in the last room) when bombs get planted, but people insist on calling them left and right. I found this highly confusing when I was new to the game, because what's our point of reference? The map? The way our characters face when we respawn? Over time I learned that it's the latter, which solves some of the confusion, but not all of it. After all, changing between offense and defense means that you're suddenly facing the other way, so right becomes left and left becomes right. All clear?
Is that the left or the right door? Depends on whether I'm attacking or defending!
Novare Coast is the only warzone I can think of where people prefer to refer to two of the nodes as east and west. (South tends to be "mid".) I don't know what makes this warzone different, especially as this one would leave no ambiguity about the question of which node is left and which one is right... if you did want to call them left and right, that is. But for some reason east and west is fine this once.
Ancient Hypergates is another confusing one because once again people don't like saying east or west, but for some reason left and right are not popular here either. There is no unique terrain that can be used to identify the different sides, so people just... don't call them anything remotely useful at all. Pylons get designated as "ours" and "theirs" based on ownership, with each team habitually going left (clockwise) from its spawn point at the start. (GD has a post about this mystery as well.) This has the potential to get really confusing if one team manages to capture both pylons, or a match develops in such a way that the teams "swap sides".
The only sort of common thread I see throughout is that PvPers in SWTOR apparently don't like looking at the map for their directions; they want their calls to make sense from the point of view of their character, as they look out on the world around them. For me this is kind of annoying because I find that the map is a much better way of keeping an eye on the big picture in terms of tactics, which is what I want to do when making calls.