It's a Tank - that fact won't change. I guess most DRK were tanks beforehand (PLD or WAR). Others just were legitimately interested to look at the class but they don't like tanking and that's why they gonna go back to their classes sooner or later.

That's said, I think the DRK has somewhat stand-alone identify problems. He does not hit as hard as Warrior and cannot eat dmg as good as a PLD. However if you wanna contribute to that discussion go to the tank forum. There that discussion is currently ongoing.