I've sometimes wished the ability to send tells or see who else is online was gone actually. At least as a trial so see how it would affect things if at all.
That would likely be detrimental to things, seeing as how while we go for immersion, it's still a game. I don't want to log on, not know if anyone I RP with, or even anyone at all, is on, and then wander around aimlessly for hours looking for someone.
On another note, I've developed friendships with several players and use tells to converse with them about things other than the game. It's my understanding a lot of people do so.
Taking these away would make the game far less a game and far more work.