You are trivializing the real markets. What makes you think this is something that NASDAQ can just "do"? They had a system problem causing delays on Facebook's IPO, and they're still dealing with the shit-storm from that now. Everyone who had poor executions (or missed executions) as a result of the delay is trying to get compensation from the exchange for their technical problem. I haven't checked the exact number recently, but I want to say $21MM is the pool that the exchange has to puke to the "plaintiffs".
Because bitcoin exchanges are not regulated in the same fashion as stock exchanges, I doubt that MtGox will be on the hook for anyone's poor executions.
> I wonder how their stack is setup.
As someone else pointed out, their stack is setup wrong if account management has _any_ impact on their matching engine. Hopefully, it was just the web servers which host both accounts-management and trading UIs. Regardless, there was clearly some resource-sharing which should not have happened.