Screw it. If you kill a NPC they are dead. There are only a small handful of quests that are required so I just need to protect those NPCs. If you go around killing NPCs then it's less quests for you.
@grumpygamer The only other valid reason to protect NPCs is when your game controls are designed in a way that makes it easy to attack by accident when you want to interact/talk instead. Which is of course the wrong solution to the problem. (I usually can’t remember which controller button does what.)