MtGox did that because they got hacked
They got hacked by self. It can not be determined was hacked by hackers or by self.
You can send Bitcoins from 1 address to another and declare it hackers for avoid taxation.
I don't disagree, as it's definitely possible, but do you have any proof that it was in fat indeed a sort of "self-hack" to steal the money of their users?
Accusation without proof is invalid however that incident isn't impossible as temptation is rising when money is on the hand. Like wth everything can happen and maybe that was just a show up.
Everytime all advice do not store btc's on exchanges.
But how to trade then.
Maybe need to develop new exchange where your deposit was in pending mode but you can trade already. And when you want withdraw you need complete your first deposit
Even they will develop that, the risk is still there since it's a third party and besides you don't have any private keys. So what for?