Making dungeons 5 player won't help. Making more tank/ healer classes won't help. Blizzard has done all these things. WoW has 6 tanks and 6 healers and 5 player dungeons. And the dps queues are just as bad there as here, if not worse. This is a player problem, the solution has to come from players. Not berating your tanks/ healers is a good start.