As you know some people are bored enough to kill goblins for ages so they can get a silly hat. (Bloodsail Admiral) However, to do so they constantly kill your quest givers or auctioneers. If it is opposite faction its ok because you can just cut them up while you wait for the respawn, if it is the same faction all you can do is stand there and take it like a man.
Wouldnt it be a good idea to just be able to attack anyone that kills the NPC's since you are defending their faction and the player is attacking them? Else you'll have to have a level 80 DK on both factions logged out in these area's just so you can give some payback :-X cant heal or buff them either at the moment and that would be a start at the very least.