Because the last time someone hacked a Sony product it ended up swell for him...
No, wait, it was a horrible, horrible mess that paved the way to having such a bad public image that when your network is pwned the collective response wasn't of outrage, but of a giant "Ha-Haa!!!" (in Nelson's voice, of course).
The issue is that consumers have a stupidly short memory when it comes to pain. How many times have you gotten called to fix a computer for someone, clean out the massive amount of porn related viruses/Trojans and get called back a week later for the same issue? Doesn't matter how many times you tell someone don't go to those sites, they still do. Why? It's because they forget the pain of losing all their crap and want the rewards of porn. Doesn't help there that it's related to a biological urge, but still.
Long term the whole PSN hacking issue will probably end up making Sony money. If anything, it brought them into the news and made them seem relevant at the time Apple and Nintendo were still getting a lot of press on their products.
People don't care. I myself have a Sony HD TV. Got it as a throw away from a friend who got it replaced due to Sony's faulty 3LCD projection light engine. A little cleaning and a replacement with some optical filter glass and its good as new. Same with the PS3 I have. The Blu-ray drive is dead, but works awesomely as a media player. Since it's on a private network dedicated to just media systems at home, it never gets on PSN. I have avoided updating it so it still runs Linux if I want, but generally I have such a low tolerance of their products that I really don't mess with it. I stream video using PS3Media Server and it works well doing what I want it to do.
I've had 3 Sony receivers. All died in a time frame that I consider short (but of course longer then the warranty period). I had a Sony stereo in my car. Even after having it replaced by Best Buy, it still skipped and had a 'tinny' sound to the music. MP3 playback was garbage. Add the TV, the 100% of my friends who had to replace their PS3 (ok, it's only 3 friends who own one, and all 3 had to replace, but still; compared to the 30% of my friends who have 360's and had to replace them, but on Microsoft's dime, not theirs) and you start seeing a trend of declining quality. I grew up with a father who told me "You can buy better, but you at least got a Sony". It probably is the reason that I have taken the abuse as long as I have. I'm sure I will have Sony products in my house and will continue to consume media/entertainment made in part by them, but will never choose a Sony product over a comparable product again.
They are now "Oh man, I had to get a Sony".