In before people say "Oh this game isn't for you" because I speak my opinion on something.
As it is now, no class can become a pure tank or healer. If you attempt to tank, even with defensive abilities, you still get face stomped by the NPCs. As far as I know, the Water Elemental is the only one that comes close to being a pure healer. Don't get me wrong, I like the idea of not needed those two roles to do dungeons and other stuff. I just wish that ArenaNet would have at least given us the choice to do those roles if we wanted to. For example, Warriors and Guardians should have been given the option to be a pure tank that can sit there and take the damage for his or her group. As for a pure healer, Elementalist and maybe the Mesmer should have also been given the option to play pure healer.
I still love the game and can't wait to play it. That is just my opinion on what I think they should have done with the class system.