I've always made this arguement and I will continue to do say in saying that each tank class has their own, particular role in this game. They can each fit into different roles and manage adequately, but have NO doubt that the roles are there. The role of the Guardian is as Raid MT. This has always been. This always will be. They will ALWAYS be best at it. Can a paladin fit this role? Sure. It's possible to have a paladin MT. Are we the best choice? Not by a long shot.
As Leawyn stated, you make a choice when you choose to play a paladin. We are tanks, yes. But we are not the best choice for raid tanks. If you go into game at this point creating a paladin to do just that, you will be sorely disappointed. We do, however, have our role in raids. With my array of buffs and AA choices, I have yet to be out of the MT group if I can make it to a raid. So, what are we? At the moment, and I specify on raids, we can buff the MT with Mit, extra avoidance, Health Regen, Sta, Wis, etc etc.