An interesting idea. Besides damage, just having evidence of being out in the world could change the way you feel about those "meaningless" quests. I remember the shock when my characters in Dragons Age were covered in blood and stayed that way. It was a grim reminder of the dirty work I was a part of. "Out! Out! Damn spot!"
Quite a while ago, I received the achievement for killing 100,000 creatures. Imagine if we had to face the horror of that "achievement" (bloody gear; persistent corpses; the haunted and judging faces of those who had to clean up; the vengeful kin; their lawyers?!). But no, we are Teflon heroes (mercenaries).