No good healer is constantly trying to top off a tank. They let a tank drop to given level of HP and then start bringing them back up (in general, shut up about tank busters, they account for 1% of the damage taken in most instances)... so vit and passive mitigation does matter. The longer you take to drop to a given danger zone, the better. If the danger zone is 1K less than your max HP or you drop into that danger zone every time the boss sneezes on you then you're forcing healers to carry you. And that is, straight up, what they are doing especially, in the case of tanks with 13K HP tanking with their tank stance off. Just let the DRG tank at that point. Keen Flurry is OP.

Use pentamelds. Full vit is for DF healers, full str is for faceroll content. If you're serious about tanking, you should maximize yourself in every possible way, not be trying to scrape by with the bare minimum.