Should players know how badly hurt their characters are in roleplaying games? You can do really stupid or amazing things when injured and most certainly so when you are unaware of the extent of your injuries.
Sure there would be extra book keeping for the GM, but why not?
Real life story-
Way back when i was 18 and briefly unemployed one winter a friend and I went sledding with tire tubes at a sand pit not too far from his house. It was a hoot, at one point however I bounced and my foot caught in the snow and flipped me out of the tube sending me sprawling head over heels down the hill, I smashed into the bottom of the sand pit and heard an odd sound that made me wonder "who dropped the coconut?" (yes that's what I really thought). A moment later I snapped awake thinking to myself "That was no coconut"...it was my head. Being the young genius I was I continued to sled for a while until my vision started to get all funky...hello concussion.
Another far more serious real life story-
A family friend has a dead relative that was shot several times on D-Day, he was likely killed (but not put out of action) by the first wound he suffered. He was instrumental in taking out a number of enemy positions that day. Finally succumbing to a shocking number of wounds. His family always wondered if he knew how badly he was hurt and whether or not he decided to die a hero or simply was one, letters from some of the men he was with testified to his heroism but not to his certain knowledge of his impending death.
My two horribly mismatched points illustrate people act without being aware of how badly they are injured all the time. Why should RPG characters know more then we do about ourselves?