Lets see...dps with all of his skills and a tank fresh level x. To enable this tank to properly tank all the skills would've to be balanced to lowi content, which would lead to the next complains that level 70 player do have all their skills but have to do their full 70 rotations to do the same amount of dps as a level x dps. I doubt that anyone wants to read the threads that will get opened when that happens.