"what if you send a man in motion and he catches a cramp? should you just audible to something else and let him lay there?"
that, or take a time out. you seem to think time outs are there for strategic clock management only. no, they are there for exactly the scenario you described.
"also, what happens when someone takes a huge hit to the head, he shakes it off and it appears as if everything is fine. the ref sets the ball ready for play, the defense starts moving into position and all of a sudden that player collapses. in this instance the player need medical attention as soon as possible and you cannot wait for the play clock to tick down and then the offense run a play before he gets treatment."
if he collapses when the ball is snapped then they don't stop play, right? anyway, the coach can take a time out, or if he's out of them ask the ref to stop play (with a penalty).
"this is the point i am trying to make... under no circumstances will they make a judgement call on whether a player is truly hurt or not. much less start penalizing teams for it. "
i'm not asking them to. but they already make judgement calls way harder than that. and they'll gladly penalize a team for chickenshit crap any time at all (cowbells, sideline infraction, celebrating, etc.).
Look, the game evolves, and the rules evolve with it to keep the game interesting and fair. if defenses start taking advantage of the 'hurt player' rule, then the rules will have to evolve to stop it. there's no need to coddle the players like you are suggesting. players get hurt, giving an advantage to the opponent. it happens! there's no need to try to eliminate that advantage. what's next, putting weights on receivers that are too fast?
here's another suggestion: play is stopped (before the play) whenever a player appears hurt with no penalty (like you are suggesting), but if he comes back in the game there is a 5 yd penalty at that time. coaches could be strategic and wait for an extra point or short punt, but they would be without that player until then.