I honestly don't get how this could be a surprise for anyone, or honestly why so many people would be upset with this. Yes it sucks, and personally I imagine that eventually my PS3 will b one of the banned ones, but if I were Sony I would be doing the exact same thing.
From what we see now, CFW gives the option of running backups, emulators, linux, etc... but who the hell knows what else it could enable? Possibly a remote attack on PSN, allowing some hacker in China or Russia to obtain other customer's credit card info or other personal info for the purposes of identity theft? That sure as hell wouldn't be advertised on any scene website, that kind of tool would be kept secret so it could be used anonymously.
Unlikely? Sure. But we don't know if it's even possible, and more importantly, neither does Sony. So if it were your network that was potentially compromised in that fashion, what would you do? I would imagine anyone would rush to close that hole in their security as fast as possible.
Hell, the most recent PSN access exploit even proves that if you can access one part of the system, you can then spoof enough legit information to access the other connected parts of the system. I guess they could just shut down PSN altogether, but compared to that this seems like the more reasonable response.