PKing was, and still is for those playing D2, the bane of many. Although no game-specifics are included, Diablo II Community Manager Bashiok gives Blizzard’s philosophical view of “griefing,” in a post on the official WoW forums.
I definitely remember running with my friends, and someone toggles it, and bam everyone is dead and your one friend is laughing. Ok, ok, good joke I guess, and then you run back and *bam*, you’ve toggled it to get them back. After a while everyone usually agrees to a truce because it’s just a waste of time. But I also remember running with random players and losing extremely nice items because of it, not cool. I’m sure that it was a feature that was right up some people’s alleys, I won’t deny there are some that would enjoy nothing more than to see others frustrated, but is that truly something that should be encouraged through design – if not directly opposed?
We have a large focus on cooperative play for Diablo III, and the mechanics and design decisions related to multiplayer are likely going to be based on supporting and encouraging it as much as possible, and not breaking it down.
That doesn’t mean that PvP won’t have its own focus, but those are details and features we aren’t yet discussing.