This is all happening because a lack of content , no good games or if they are good the prices have fallen enough that they are easier to buy then copy.
Im betting a bad economy has a huge role in this as well , maybe most of the folks who used p2p to get music have found other means , or are using encrypted means that can't be distinguished yet ? -- "It's always funny until someone gets hurt......and then it's absolutely friggin' hysterical!"
You can't forget that distribution methods like steam have pushed gamers away from peer to peer. It has (nearly) all of the convience of downloading the game illegally except you have to pay for it and don't have to worry about viruses (a very nice tradeoff in my book).