You can probably make them optional if you're a decent shot with the rifle Cruel jokes aside, yeah, that seems like a good idea. Some players like them, some players don't. We already get to choose between four different experience modes, so a simple "NPC's yes no?" box to tick probably isn't too much to ask. Personally, I'd like to see some NPCs in my sandbox, but still, I can see the appeal of not having them there.