Anti-pk doesn't mean that you don't kill, it means you don't shoot unknown people on sight and you shoot people who do it. It's actually a lot more challenging style of play, because you don't have the privilege of first shot, you can't kill random scouts and you can't use many dirty PK tactics. Being a PK doesn't make you cool and badass, just cheap. But it's good that some people play the role of wasteland losers, otherwise it would be boring.