Indeed, very interesting discussion, also from the perspective of new member of community, as me. Some thugs from Khans (respecting their privacy, called "Mr x and Mr x" for the purpose of further story) were main PKs, who teached me how harsh PK could really be in practice in fourd or fifth day of my game (i.e. about month ago), where leather armor and .44 was my best gear.
So, I generally fully agree with Mantis. From the beggining (I mean, since the first time I was slashed by PK i.e. probably first day in the game), I was very excited about threaten related with activity of PKs. This encouraged me to try to learn very quickly about the game (via forum/ Wiki), both in terms of mechanics and general info on tactic; simply everything, which inrease survivability in the wastelands.
Then, one day I faced Mr x. This appeared to be really unlucky day - unbelieviable, he somehow managed to meet me in various encounters 4 times within approx. 15 minutes. As result, I literally have lost almost all caps and gear, which I collected from the beggining. Communication with Mr x was 'interesting', as he role-played to some extent. As he ordered me to do something in very offensive way, calling me fagout/ nigger etc. I refused (especially in further meetings, after he had vomitted and pissed off at me) and obviously got killed each time. There was little room for reacting with humor, or maybe only I am just not good in jokes, when acting under time pressure. At least, I succesfully managed to let Mr y tasted my bullet, when he accompanied Mr x last time we met.
What the above lesson gave me (apart from 10 minutes of anger and frustration) is great will to learn and develop in the game as fast as possible, so one day I could ask Mr x for papers and punish him, if he fails to present them, as he did to me. Nevermind, if I managed to do it before wipe (I doubt:) or if I managed to do it anytime in the future (hopefully I will), this (and any similar situation in the future) will make me to play hard for months or years. Initially, I suspected Mr x of sadistic/ sick mentality, but after some time I realized that it might be just his way of contributing to atmosphere of Wastelands (altough those two theories do not need to contradict to each other). The latter theory was further confirmed after reading forum, watching Mantis' tutorials on youtube (well done Mantis!) and finally by above speech on Mantis' philosophy lying behind player killing.
To conclude, I support above philosophy and and believe that player killing (even such hursh, as Mr x does) is great part of this game. Very motivating (I am not taking about baseraping, which has not happened to me; but just in case I keep valuable gear in number of houses, to mitigate potential losses), making the game exciting and interesting from the very beggining. Another good thing is that it may naturally eliminate players, who are not enough adult to understand harshness of this wastelands and not enough smart to survive. My first impression on the game is that the community is small, but more 'valuable' than community of most of other games I played before and I assume that PK have their material role in this.
The only approach, which I personally disagree, is the approach of PKs (allegedly being shared by 10/10 Khans, according to above comment), which say that they do not kill noob, if he does whatever they order him. Such misery players, letting themselves to behave like slaves, should be eliminated ASAP. Such behaviour would disgust me rather then entertain. If I find PKs amusing one day (I doubt that I will do it regulalry, but maybe on occasion), I will save lives of those, who will react with honor and/or humour. But this is of course only my personal view.