The Recording Industry went after them because they were the most popular of all P2P programs. It was actually easy for them to get taken down because they kept a listing of what was being offered on their servers. Current P2P’s don’t do that and create direct connects from one user’s PC to another. Kazaa is the other latest casualty.
It’s a waste of time to take down these p2p networks. For every 1 they take down another 10 pop up. Besides, bittorrent is even more useful than p2p now. Although I still use SoulSeek for music.