While I like the strategy based on role that you get with the trinity, it really does limit large groups of people--guilds especially.
For example--I like playing my tank in ToR. I hated it at first, mainly because I thought my sin would have a different role, but I sort of naturally progressed towards a tank build without realizing it...then you realize how in-demand tanks are in that game. Queueing for HM FPs is instant with a tank. With my DPS, ....forget about it. And the role of a tank is quite demanding--it involves patience and experience, but of course once maps and mobs are learned, no less grindy than any other role.
The problem with this, though, is that if I am not around, "raids" don't happen. Pugging a tank is a far different proposal than pugging a DPS, or even a healer when doing OPs. To me, that is a game-breaking model....by design. WIth so few people rolling that class, many, many people are limited with what and when they can play, because someone is simply not around to fill that role.
I like to help and I like to work with groups even though I get no useful gear out of runs, but it bothers me that in some ways, there exists some implied guilt if you aren't around to fill that spot, so no one else gets to go (not guilt from other players, just, you know--sucks that you guys can't do it because I'm not around, but....whatever?)