Mary, the pk point system will only be effective if it is encumbered by severe restrictions, for any form of abuse would make it redundant. The skill-level hiscores CANNOT be unfairly tampered with (except by botting, in which case you receive severe punishment), whereas PvP hiscores can easily be unfairly tampered with. The difference between the two is enormous. Sure, they both record progress, but that's where the similarities end. A PvP system will always be open to being abused for points.
Ekke, please do not compare two scarcely related things. If you insist to, then at least provide an effective argument to support it.
Yazan, the wilderness is a place for PvP to occur WITH RISK. It is not a place made to kill people who are spectating fights. Yes, you obviously can kill them, but no one does because there's no purpose. If a PvP point system were to come into play, there's a strong chance that spectators will dwindle, which takes a great bit of fun out of pking.
Regarding your point of only receiving points when there is a loot, Mary, friends can easily abuse this. Some people might even use this as a new way of legally scamming people/friends.
Regarding the point of spectators being killed, perhaps there could be a toggle that one can use (only can be toggled when OUTSIDE the wilderness) that sets your character to either being able to PvP in the wilderness or not -- maybe giving the player an icon to show this has been toggled on/off.