To be honest, and I say this as both a fully geared warrior and paladin-- warriors currently don't offer me any advantages whatsoever compared to paladin. And I'm glad SE noticed, and is going to be addressing that, presumably by buffing warrior mitigation.

But until they do, the tradeoff is basically:

* Bard has to play TP song for warrior, making the BLM slightly slower.
* Healer has to focus solely on warrior, can't DPS as much.
* Warrior has less defensive cooldowns, making point 2 even worse.
* Warrior has to skip some pulls "to be safe" if he wants to stay in speedrun time limits.

By no means is it IMPOSSIBLE to use a warrior tank and kudos to those who stuck through it, it's just more optimal to use a pally right now.