Look, the point is, its a bit like blaming a home owner when there house is left unlocked and subsequently burgled. Just because they made it easier through some inaction, at the end of the day it is the perpetrator of the crime who is the real villain.
Bullshit.
You have no responsibility to anyone but yourself (and perhaps your family) to lock your own front door.
When you take other people's money in trust, you have a fiduciary duty to protect it. Incompetence is a breach of that duty. Outright fraud is an even more unconscionable malfeasance. Karpeles and Gox (if they even are separate) utterly failed to carry out the duty they'd agreed to by accepting deposits.
This is assuming, of course, that he isn't actually the thief himself, and frankly, I'd put him at the top of any suspect list.