I hated quests that required killing an NPC because the game felt empty enough already. I would actually use cheats to resurrect NPCs afterwards just to have more bodies moving around.

I will give them credit for giving the NPCs homes and schedules. I love it when games have the NPCs actually live their lives like work, sleep, go to taverns, etc. You lose immersion in a game when the NPCs are perpetually glued to one spot.