PK is boring.
Farm is exciting.. if the server is secure and stable.
It's how KO has and how most MMORPG's and MMO's are.. why you would want to just go into a game with the best gear and kill eachother is beyond me.. I find it highly boring and it really doesn't entertain me and I am sure most people would agree. Besides? Theirs more money to be made in the farm servers than a PK server.