Step back from what you know about how popular certain classes are and reconsider the acclaimed LFG tool. The slots are for one healer, one tank, and three DPS. From a naive perspective, the non-DPS classes are getting screwed here. It looks especially absurd coming from City of Heroes, where support stacks nicely and groups are often more than half support classes, or The Lord of the Rings Online™, where an ideal six includes an off-tank, secondary healer, and/or controller/debuffer. Cap the group at one, while the DPS classes get three slots? It would seem like you’d have a much easier time finding a group as DPS.
But no, the population is so absurdly slanted towards DPS that they are waiting. Tanks and healers queue and instantly get groups. This is still true even now that people know they can skip the queue by switching talent trees, and few groups are going to kick you for having lousy tank or healer gear. Granted, if you are a Mage or Rogue, you are stuck as DPS, but that Paladin could spec and queue as any.
A system that explicitly favors a preponderence of DPS is de facto the largest buff to tanks and healers ever. This mostly comes down to what I said about static groups: anything that makes grouping easier makes group-friendly classes and builds more viable. As the population has time to react, group-friendly classes and builds will become more popular.
The upcoming Star Wars has a different approach: the Jedi/Sith classes are the tanks and healers. If you want a shiny lightsaber, you don’t get to play DPS. Yeah, right, I say that, but you can already hear the forum wars mockery of all the Jedi/Sith that focus on damage. “DPS Sith lol. Can we get a tank that can tank?” Or, as DK tanks currently say, “But Blood Stance heals me!”