And don't forget the casualties healed for the winners at the end of the battle although sometimes it's almost look buggy.
What I mean by that is that some badly mauled units get no casualties healed and some units who were wiped out got all of them healed back!!

The only thing I could see, to achieve your idea, would be to make men more difficult to kill but units easier to rout. That way, generals would have to be careful when engaging the enemy because of fear of mass routing.
But yet I can see that the AI will probably not care as usual and get routed all the time quickly

Anyways, just my