As long as someone has a healing spell available, I think it's quite harmless to auto-heal everyone once a fight is done. I remember it was partly annoying to fully heal everyone after a hard fight, waiting for the cooldown between each cast. And that was only with 2 chars.
Maybe after a few seconds have passed though, as I can envision a few exploits with this suggestion, like getting into combat on purpose just to get the auto-heal. For, like, getting through a trap-filled room or something.
