Sometimes I wish I hadn't had such an effect on the world I'm in.
In Oblivion my thief-type guy developed a habit of killing just about anyone he came across and could get away with killing. Since named NPCs don't respawn, though quest-related ones will be merely knocked unconscious, this meant that by the time I was done, I'd killed off most of the wandering civilians and about half the shopkeepers. The streets were strangely empty, even before the demonic invasion.
When I made a caster-type to see how that would play, I was confused at the NPCs all over the place, talking and gathering here and there. The shops were even filled with goods. How odd!
Similarly, my guy in Stalker was curious about what would happen if I shot a Duty guy in the face. That's the big militant group that I mentioned before. Well, they called in a lot of help, including from sympathetic non-member. The result? Half the trade hub dead. They have ever so slowly been respawning with new randomly generated names, but it's still a bit more empty than it was.
This brings us to the strange problem of MMOs with factions: we want our enemies to die and stay dead, but it's not fun having our own cities emptied out. Since one faction's enemies are the other side's allies, everything respawns. Nothing stays dead, whether we want it to or not.
There Must Always Be a Lich King.
If Grommak the Ham Merchant dies, let Grimmok take his place. We might not notice the names changing, but it's at least a small acknowledgment that we did actually kill someone, without causing mass complaint over the sudden inability to purchase hams in Orgrimmar.