Do you realize that doors in City are also arbitrarily-locked? We can withstand rockets and toss 2-ton titanium robots like ragdolls, but we can't open a stupid wood door if we are not in a mission, or a certain moment of the year ? It may be true that the game would feel bigger if all those doorways were closed and you thought there are can be an infinite number of things on the other side of all the doorways, but it's also nice that you don't have to reload every time and it feels more real.
In CoH, the doors are eye candy unless you have a mission -- the instance you enter isn't
part of the zone; in SWTOR, you can
see into the screened-off area, but can't go inside. To make things even
more schizoid, while in some places you have your conversations inside a walled-off part of the map, there are others -- on Tython where you talk to the Jedi Council shortly before leaving for the Republic fleet -- where you walk up to the door, click on the door, and then everyone else sees you just standing there with the little 'conversation' icon while you have your personal cutscene; apparently it was too much trouble to do it consistently one way or the other across the game.