- Tank (Ironbreaker, Black Orc, Knight of the Blazing Sun, and Chosen)
- Healer (Rune Priest, Goblin Shaman, Warrior Priest, and Zealot)
- Ranged DPS (Engineer, Goblin Squig Herder, Bright Wizard, and Magus)
- Melee DPS (Hammerer, Orc Choppa, Witch Hunter, and Marauder)
When you have hybrids that mix DPS with another role, like what we appear to have on the horizon for WAR, there is the very likely possibility of people who pick one of the Hybrid classes and plays it as a pure DPS class. So you seek out the hybrid class so that they can do their hybrid thing, but they only do half of it, specifically the DPS half. While I'm not going to complain because the enemies die faster, if I'm tanking and the healing-type guy I've brought along is only smashing faces I'm gonna be pretty pissed, I have to say.
Addition: To elaborate, this goes both ways. By choosing a tanking role, I am accepting the mantle of a guardian. My duty is to protect those who cannot take the hits as well as I can. When people die near me, if there was more I could do, then it is my fault, and they will have every right to be pissed off as hell at me.
Now, obviously if you've done everything you can to protect them or heal them, or whatever, then only fools are pissed. But that's not what I meant. As I said, if they or I am too focused on hitting the target in front of me, and not doing everything I can to help everyone I can, then I've failed. That's the potential fault of having a hybrid DPS/Healer or DPS/Tank.
At the same time, it's really more of a fault of the player than the game itself. In the hands of a smart player, such a class is a great tool to be put to good use for all. In the hands of a moron... well, let me say that the enemies will be happy they won't be going up against a serious threat.