@Callinon: Guild Wars 2 did away with the trinity system and introduced other party dynamics in its place. The problem wasn't with this particular decision, but that they failed to balance those party dynamics so that they were actually viable. I mean, you can shoot an arrow through a wall of fire and it turns into a flaming arrow. Cool! But, unfortunately, pretty useless. There are plenty of other games that kept the trinity and because of their failure to balance the trinity, it ended with the same problem... the party dynamics were still basically nonexistant. Moral of the story; it doesn't matter what your party dynamic is if you don't actually balance it.
You could have 100 different roles; it all depends on the foundational mechanics of the game. More roles or fewer roles aren't inherently better or worse. (I'm just pointing out that developers lazily glorify the trinity system without actually understanding it. It's not that the trinity inherently facilitates strategic party play or anything like that.) However, the more roles you require for a functioning party, the more you limit player abilities to build a functioning party. If any mishmash of roles will do, then a party finder is completely useless. My point being, if you don't create the problem, you don't need to create the solution.
Edited, Jan 9th 2013 10:07pm by Kachi