mtgox is an exchange, not a bank. it's banks business to speculate with clients funds. exchanges don't (or shouldn't).
They're not an exchange. They're a pretend exchange of a virtual currency. Post a link to the rules/laws/regulations MtGox, as an official "exchange" of Japan has to follow. Do they really report to the JFSA (Japan Financial Services Agency)? Come on now.
of course they are not an official exchange, but they work like an exchange. still, you can't compare mtgox to any banks.
So they don't have to follow the rules of a real exchange, but they're going to anyway? MtGox can (and has and does) spend the money that's been deposited. You really think they keep 100% cash on hand to cover withdrawals? Really? They never operated at a loss? They have mountains of cash on hand to cover everyone? People really trust them that much?
You're saying that regulated banks spend/gamble clients holdings, but an unregulated bootleg bitcoin exchange in Japan, they'd never dare use clients holdings to cover investment/expenses/costs? Come on now.