My group of gamers started at 15 and over the past 2 months that number has dwindled to 0. I was the last one about a week ago. I'm sure this is happening all over the place, and it's due largely to the server pops as people have mentioned in this thread, as well as a pretty lame endgame.
The game just gets old after a while in general. It doesn't really bring anything new to the table other than the questing and overall setting.
We were big pvpers also, and got burnt out on the grind.