It wasn't long ago that everyone was gawping at some 425k coins being moved, presumably offline by the MtGox lot. Then there are 50,000 users they have picked up in the last month. (I was about 11,000 and I signed up on June 1st, there are 60,000 odd on the list now!). They offline most of their funds and just keep a float, hence the maximum withdrawal limit.
All the coins that people see trading are all just numbers in a database. The hacker clearly had much more control than is being let on, I would imagine he ran a SQL script of some sort to dump all of the dbCoins into one account and then put in a sell for next to nothing.
MtGox cannot afford to honour all of the coins. That is all of the coins they have, and everyone else who is daft enough to leave their coins on a public exchange run by beginners. If they honour your claim, there is no more MtGox and everyone and their mother will be up in arms, litigating, leering and generally ousting them from the community they have helped to build.
The bottom line is that you are losing the coins no matter how much you complain. You say you should keep them for the good of the community but if you've got half of the freely traded bitcoins then the market really is gone. Tough luck.
This.
It is clear now that MtGox has not been trading bitcoins but a representation of bitcoin, storing the real bitcoin off-line from the trading accounts (the one big centralised 500k account).
More centralisation, more fail. It is like the fiat credit crises freeze all over again, the bitcoins weren't really there and when the hackers showed up there was nothing to go around and fill the gaps, even if they took nothing, just shuffled things around and messed it all up.
Lesson learned, move on, decentralise. Get bitcoins in your hand or you got nothing but promises.
EDIT: By storing the MtGox float in one account then they have become a counterparty to all trades by proxy, i.e. a market maker. Not what is claimed up front.