The idea of the post at least when I started wasnt related to called shots. Just that critical hits may cause effects that arent just damage, like they hit your eye, less perception, leg injuried -25% movement; finger crushed less attack, bleeding you lose some hp per second, and so on. Few of these effects maybe hard to recover from, needing hard to obtain items or miniquests, or something different to a spell that the party have.
As some people said, 'semipermanent' shouldnt be something usual, or it would be boring and a chore, I agree. But if it happened eventually, it should give more deepness in my opinion, or as someone said, in an ironman mode.