Mt.Gox itself was hacked not just a guy. That's a bit like Wall Street being hacked, with due proportions. Also, Mt.Gox reaction to the episode is apparently pissing off a lot of users, as per comments in linked page.

I don't think this is the end of bitcoins but surely enough is quite a ouch moment.

Lesson I've learned today: given that bitcoin wants to be a better currency, they have the chance to provide a better service. A good bitcoin marketplace should enforce two way authentications, maybe with yubikey or even just GPG keys.