If dps have to do markedly more damage than tanks and healers in order to preserve their identity, then they also need to have markedly less defense. Getting cuddled by even the softest of mobs in dungeon or raid content as a dps should oneshot you. It should be to the point where you're scared of even peeking around the corner without a tank in front of you, let alone pulling for your tank.

If that's unfair, then let us do equivalent damage, because our vaunted defense doesn't count for much.