I second this. Reason why we have tank shortage in 4 man dungeon is because there's almost no incentive in doing it. Sure they increased the rewards in Duty Roulette, but that can only be done once a day and the rewards actually, well, it's not worth it.
If the mounts weren't supposed to be a solution to the tank shortage, they should've just given it to the tanks who've been tanking since X date. Pretty sure there's more to it, but it just didn't "clicked" due to lame implementation.