I like some aspects of a trinity. Personally, I thought dungeons in GW2 were miserable without one. The rest of the game I think does just fine without one for the most part, unless you happen to be that unfortunate individual who gets focused by an event champion you can't shake -- incidentally, such things really make me wish that all classes had some sort of aggro dump.
However, I love hybrids too much for a strict trinity, which is what happened with WoW. You basically traded off hybrid utility to compete with "pure" classes. Tera was like that too, although, it never gave you the option to be anything but what you were. The classes were too distinct to the point that I felt pigeonholed into the equivalent of one of WoW's talent trees.
I'd say if anything the thing I miss is being able to "save" people in GW2. I can't taunt a mob off someone nor can I typically heal them (even when I can it's not enough to matter). People complain about the lack of team work required in GW2, well, it's basically designed that way. Many of my alts have no good way to assist others, so that makes it all about me and everyone else is on their own.