paxx, you are a genius. You approach this issue with a clear and analytical mind.
I believe the question of player killing (and if people will abuse it) is philosophical in nature. People don\'t seem to see it from a global perspective as they should. They are too busy imagining their fantasy game where they can indulge their sick desires to kill everyone around them. That is, to be A GOD. Many single player games allow you this luxury, and I imagine some have grown used to it and would like to experience the same thing in a MMO environment.
The trouble is, nobody wants to be the little guy. Everyone wants to be the one with the power, not the one without.
So, it becomes a quest to quickly increase the power/experience/stats of your character in order to exact your revenge.
This negates the purpose of a Role Playing Game. And it becomes a deathmatch.
In a typical role playing game, you, your character is the hero. And the hero is never easily killed.
In a MMORPG, EVERY player character is the hero (or villain, or whatever)--even the newbie. And none of these heros or villains should be easily killed. They are the main characters of the story, and their battles are meant to last a long time.
They are clever and quick, can detect assassination attempts, and can never be killed by a single blow. They can catch the arm of a thief before she makes away with their loot. If a battle cannot be won, they can always run.
So, thieves and assassins are best focusing their efforts on NPC\'s as player characters are a fools target.
Everyone is the main character of this story, so everyone must survive till the end. PKing is removed so this is possible. (NOTE: there is still death from mobs, but as in every game, we ignore this and pretend the hero character never dies. (IE. we pretend he never dies by bringing him back to life))--i may need to think more on this point...
I also believe the greater the amount of player interaction, the more interesting a MMO game becomes. So, keeping player interaction high is important for a good MMO game. Pking is interacting, yet it still needs to be perfected before it can be used properly.
Paxx, I hold you among the highest of the devs.