You're legit complaining about self-sustain in the lowest possible denominator of content...dungeons that means absolutely nothing apart from a means to get exp or get tomes as quick as possible, period. So what if tanks can recover a healer screwing up and saving a dungeon boss, "oh the humanity!" even though Paladin has been doing this for the last four years. ¯\_(ツ)_/¯

you will need to wait until normal mode raids come out, or even more preferably Savage before you can even remotely get close to a baseline average to see how tanks are actually performing, as dungeon content is no way remotely close to a means to balancing jobs.