But... whenever somebody tries to make a game which questions that assumption, such as World of Darkness ... players make the mistake of maintaining that assumption and getting frustrated at the rules for "punishing" them when (they) go around killing everyone in their path and stealing everything that isn't (or even is) nailed down.
I would have to say that if
the players themselves are "maintaining that assumption" (i.e. that realistic representation of the long-term psychological trauma effects of personal violence is, for most groups, a net negative for overall game enjoyment) then they've just by definition proven that it
isn't an assumption, or a mistake.
They waste all that effort whining and complaining and making cheat pieces when they could just play with a normal chess set.
They could, but the problem there is that there are many ways "chess sets" are not created equal. It's not unreasonable to complain that a particular game which does give you a gameplay experience you really want (e.g. being a badass vampire creature of the night) only provides it at the price of enforcing a gameplay experience you really
don't want (e.g. rules about losing conscience and humanity that strike you as either unrealistic or uninteresting).
Part of the difficulty with WoD games in particular, I think, is that they try to have it both ways: they want to make it possible to play as both action-packed urban fantasy adventure
and as intense interior psychological existential drama, without considering the possibility that these modes are to some extent mutually exclusive -- if for no other reason than that sheer weight of repetition, in any ongoing long-running game, will undermine the dramatic impact of any particular psychological trope. Consider the need to hunt and feed in a
Vampire campaign: almost without exception, such scenes get played through maybe once or twice "on stage" at the start of the story, and then are handled with quick "off-stage" die rolls for the vast majority of the rest of it. (At least in my experience.)