@Cognitive there are no levels.
@Gothix I think "losing time" is more about the fact that some activities in mmo are boring (grind, gathering resources etc) but we do them so we can do the more fun things later. In open pvp with full loot you can lose all things gained from the boring part without getting to the fun part. For PvP player it's not a problem - the way he died was the fun part for him. For PvE player it is a problem because he died at the boring part and he will have to repeat it.
A very unfair for PvE player comparision would be: sheep want to just eat grass, wolf want to eat sheep. You put them both on field of grass and say "now you both can have what you wanted". But that wouldn't be much fun for the sheep
And I hope that you're wrong about there being a large population of people that want to kill others without challenge or consequences.