I think the difference is that you can tank low level dungeons in any gear but at 85 you have to run heroics as dps until you have full tank gear before you can tank. All they need to do is make entry level tanking gear easily accessible. Make leather workers and blacksmiths level their professions by crafting tanking gear so that people who WANT to tank CAN. I would love to tank from the start at 85 but it takes forever queueing as a dps, building dps gear, and then eventually building tank gear when the tanks don't need it. They want to encourage people to tank as much as possible but then they make it so that you can't tank until you have all your gear and once you have all your gear you dont need to run heroics much anymore. Let me get easy tanking gear, then Ill run heroics as a tank in order to get dps gear. That'll result in me queueing as a tank at least twice as many times before I'm fully heroic geared in both specs. Problem solved.