I am glad GW2 doesn't have the holy trinity, and I say this as a person who loves being the healer. I like dpsing and tanking is okay, but healing and supporting my team is where I get the most enjoyment from. In GW2 I can support the group and contribute in other ways, which is amazing. It also means that when I decide to NOT play on my healer, I don't have to worry about some "baddie" keeping the group up while I play on my elemental shaman. Without the holy trinity, I can support my team while killing things, or kill things while supporting.
I am hoping more games follow GW2's suite, but I doubt it.