Bitcoin just suffered a loss of 6% of its total currency
No, Mt. Gox just lost (most probably) all of its currency. It is similar to a bank with insufficient security getting robbed. That is no reason to ban US dollars. BTW, those BTC are out there and will no doubt be spent over time.
, if I understand the Mt.Gox math properly (and even if I don't, the loss was significant). One of the reasons governments came into being -- one of the reasons most people tend to agree that they should exist, is to protect property rights. There may be nothing wrong with Bitcoin inherently (mathematically), but if there are holes in the faucets -- the bitcoin banking system in this case -- then it's in everyone's best interest to patch the holes.
Indeed. However, other exchanges were smart enough to protect against this well known technique. Mt. Gox is the equivalent of a bank with a faulty vault and no security guard. Rumor has it that Mt. Gox hadn't balanced its books for months. Inexcusable.
If someone steals my money, then the taxes I pay go, in part, to pay for the legal system, rules, and police whose job it is to try and get it back or at least punish those who took it.
Bitcoin has had four years of freedom, and it has proven that it is as susceptible to abuse as traditional cash currencies, if not more so. While I don't want to see it crushed, and I'm in favor of limited government oversight, it seems to me that those limits should be non-zero.
The Japanese authorities should be making some effort to track the crime. Unfortunately, it's about the same as if a bunch of gold had been stolen from safety deposit boxes and shipped out of the country. There's likely no recourse, but that's no reason to ban gold ownership. Personally I think it's wiser to keep one's gold in a safe at home - and there is a BTC equivalent for that.