There is a great post over at the ArenaNet blog about Guild Wars 2 professions (i.e., classes) as playstyles rather than roles. Peters writes that they designed the profession and combat system so that each player can fluidly adapt to the battlefield in order to support allies, control enemies and the flow of combat, and simply damage enemies. He presents a great analogy:
In a first person shooter there can be a variety of weapons, from sniper rifles to rocket launchers to machine guns and shotguns. No one looks at these weapons and says, “They’re all the same, they all just do DPS.” Why should an MMO be any different?
I was playing Team Fortress 2 last night, and I thought nearly the same thing. We were playing Hightower, and two enemy engineers decided to really shake up the battlefield by planting mini-sentry guns all over the map and then attacking aggressively with the crit-laden Frontier Justice shotgun. In a role system, the engineer is supposed to be on defense sitting behind whacking his sentry and shooting at anything looking like a spy. Yet, the loadout system in Team Fortress 2 lets each class respond to the battlefield. For the engineers last night they wanted to own the battlefield until the opposing team responded. As we were on a public server, those two engineers used that tactic for quite some time successfully before we slowly and stupidly responded.
Anyway, I feel the skill and trait system of Guild Wars 2 is going to do nearly the same thing. A guardian is going to be a “master of defense.” Yet, a player that writes off a team of 5 guardians as too defensive is going to be pretty surprised when he gets cut off from his team by wards and then pummeled and burned to the ground by 5 guardians with their spirit weapons chaining the Justice virtue. Players are not going to simply be able to respond to the opposing profession. They are going to have to see how the player is using that profession.
Add Guild Wars, Vindictus, Dragon Age, and a pinch of Left 4 Dead 2, and I think the result is going to look a lot more like Guild Wars 2 than starting with a base of any conventional MMO. The whole article is well worth the read as Peters discusses other mechanics that shape the combat system such as the heal slot or the shared boon system.