Keep in mind, there are ways to go about killing people that are more 'legitimate' than just deciding on a whim to murder some poor guy. For instance, join a mercenary force or a bounty hunters' guild. Or, get named a sheriff or deputy on some backwater planet and chase down a few criminals. Or, hell... go join a band of pirates.
The point is to keep people from doing nasty shit without having any kind of justification as far as their character's story goes. We don't want people to go randomly gunning other players down because they feel like it.