I absolutely believe that I should have the right to do whatever I please with the hardware I purchased. If I want to run a hacked software build on my PS3, then I should be able to do that.
However, I also defend Sony's right to say "As long as you are running that hacked software, you can't connect to our network". That's an entirely reasonable thing for them to do,
IMO. They have no idea what the state of that system is; for all they know someone could have loaded some kind of virus on it to take down the entire network.