If you're running on adrenaline to keep you up mid-fight while you have a broken leg, or a broken collarbone, or you should collapse after the fight is done, that makes sense. But it sounds like you're saying it's reflected in the game, but it's not. The broken leg is not reflected in the game, nor is the broken collarbone. And, realistically, if you did have a broken leg, you might be able to push yourself through it and keep fighting (and it'd be cool to see in a movie or read in a book). However, if you can keep walking around on it after the fight is over and the adrenaline is gone, and perform just as well in the next combat (and be just as nimble and mobile) as long as you aren't hit, then I think the argument you originally put forth doesn't work out.
But, I might be missing something. As always, play what you like