I only really did any killing of innocents in Fallout. I felt like it was something that a person lacking morals might do in a post-apocalyptic setting, and on my "bad guy" character I would sometimes kill people who had something I really wanted, or needed. However, in TES there is still rule of law so you're basically just a serial/spree killer. Which is a weird thing to RP in a fantasy setting. Whatever though. Sometimes I will save the game, and kill people, just to see what armor they have, and then reload my game. Thats about it.
EDIT: Just wanted to add, that if half of the fun was random slaughter, roleplaying games may not be for you. Where's the story in that?