From what I've been reading in the forums, one of the most convincing arguments for me is the static vs dynamic mitigation. It seems most logical that the trouble WAR faces is that they can't scale their way of tanking against incoming damage like PLD can. I think all a WAR really needs is something that scales against incoming damage. Maybe some kind of CD buff that lets you take a percentage of incoming damage and heals you for that much. Or maybe each stack of Wrath gives you a percentage of incoming damage as a heal or something. That way, even if newer content comes out with bosses hitting harder and harder, WAR will still be able to dynamically handle it just as a PLD can.