No idea about you, but I dislike that mobs can heal through walls.. just like they "may" dislike that we can heal through the wall as well. Heal spells do not need line of sight to land.
I was just retrying AltAdv in warrens and found bit hard that creatures were healed over and over the walls of that dungeon - shamen were close enough to heal, but not in same room, not in sight.. all those duhh kobolds are in same group it seems, huh?
What do you think about this game rule?