In a hierarchical organization, change happens by fiat from the top down. In an anarchic place like the internet, shutting down servers through legal attacks serves the same purpose. It sucks for the server operators, but it forces users to try out newer and different solutions, which are often designed to fix old flaws. If you like analogies, the RIAA is like a fire that cleans out the deadwood.
Grandparent is pessimistic because he thinks piracy can be stomped out.
I believe the opposite, but I am still a pessimist. I am pessimistic because I worry about what will happen when the pirating masses will go underground when they are labeled as criminals.
BitTorrent is elegant but not really trying that hard to hide what it is transferring. Consider it a solution when Napster failed: The centralized server was the weakest link, so the new protocol operated without a centralized server.
The attack now is on surveillance on peer transfers. There is a solution, there have just not been any need for it yet. Distributed hash tables, strong encryption, onion routing. (Outlaw encryption? Hello, Steganography.)
The pessimistic part:
Treating masses like criminals accomplishes nothing except hiding the heavy criminals. The tools that will be created for safe piracy will likely also make it that much easier to transfer any other information, be it terrorist briefings or child porn.
Much like the prohibition era, trying to apply a law against the will of the masses will not accomplish much except benefiting criminals.