It should get nerfed as the playstyle it encourages is, well, wrong. It forces you to get high Con, just so you trade most of your hitpoints into massive critchance, changing your tank into glassiest of cannons. It makes no sense from character building perspective. The feat should promote risky tanky playstyle, not forgo the tanky aspect.
I would change it into something like: gain 1% crit chance per 10hps lost during last turn, up to 30%, for the next turn. Reward tanks for tanking instead of turning them from tanks to twigs.
EDIT: Damn, Shoggothwhisperer came up with similar idea already....