Not disagreeing that it hasnt happen. However we arent talking about a common practice.
Its like stealing cars. Doesnt matter how secure your car is, there are groups that will try to steal it. However making it a bitch to steal is where my point is.
Sony clearly underestimated this issue and had to learn the hard way. I am sure most companies have. In this day and age, if a company tries to do online and havnt thought about using beefed up security, than there are trust factors and inexpensive at play here.
You're either out of the real world or joking.
Government's data breaches are far more critical (OPM is one of the most significant data breach known at this time) and common than you think (try a search whith IRS, USIS or KeyPoint for the most recent).
To compare (and minimize) these attacks against the single big attack of the PSN (as unacceptable as it was, data was less sensitive) is quite inappropriate.