"Hey I didn't say it was right did I, it still sucks and shouldn't happen. Like I said though, perspective..."
No, I just think your perspective and those of many others, is distorted. This isn't minor, the details which were leaked are very sensitive in the wrong hands. Details such as name, address, email, last four credit card numbers and recent purchase history are more than enough to commit fraud or phishing attacks.
It was also hugely inconvenient, like many people who logged on during that period and discovered they were looking at another persons account I immediately called my bank and cancelled my card. There was no information from Steam about what was happening and I wasn't going to risk some stranger racking up purchases on my account* - even if they might have been refunded later. So now I'm without access to my current account for the next few days until a replacement card arrives, during the holiday season ...
* Yes, it would seem that this wasn't likely to occur now that the cause of the problem has been revealed (albeit not directly by Steam in a message to their customers), however it was impossible to know that at the time.