Because players can do things to make content and make things more fun.
They do. I have another thread about that. I've done seemingly all I can with pvp in this game. The only suggestions people seem to have is that many of the original pvpers are going to take a break and see what pvp content comes with 1.7/Hutt.
But here's the rub. There are two sets of people in an MMO.
Players - Those who pay and play.
Developers - Those who are payed and continually develop content.