In my experience, Guild Wars 2 is a good example of a game that allows diverse playstyle. All jobs can play any style they want... warriors can be healers, or mages can be meaty soldiers (no tanking in the game, but still you can be very tough). There are also many ways to deal dps for each job, be it direct damage, DoTs or pets. Granted there are "optimal" builds for max deeps enforced by elitist speedrunners, otherwise every other build you can think of is acceptable and playable.