That's not a bug, that's a feature!

There has always been one thing in MMO's that anoy the heck out of me, i would be out exploring or doing some quest, you would come across a named mob or someone askes for your help killing a mob and you kill that mob.
Later you get a quest to kill that excact same (named) mob, i see this happen a lot in WoW, but it's not only WoW, i see it happen in most, if not all MMO's.
Eventhough i am not a hardcore roleplayer, i still feel it is wrong, afterall i allready killed that specific mob so why make me do it again??

There has been one MMO to date (that i played and loved) that got it right: Tabula Rasa!
There were several times where i would join some people in defeating a mob or i would be out exploring and encountered a mob and killed it, than later when i would be out questing again and get a quest to kill a mob i allready killed before, the quest would just auto complete, almost like the quest giver would say "ah i see you allready killed him, good job".

I would say that's one heck of a feature and i would love MMO developers to take note of that and implement it, afterall most MMO's log everything you do in game, in WoW for example the game knows if you kill a boss in a dungeon, it shows up in your armory feed, (heck they even know what you're looting) so to me it would only make sence that if i would recieve a quest later on to kill that same boss in a dungeon or the world the quest would complete, because you allready did "the job".

To me it's not a major thing but it still anoys the heck out of me, having to go back and kill the same mob again and like i said it makes no sence to me, maybe it's just the little roleplayer in me, but it just feels wrong.