To me, one of the more interesting results of Bitcoin is how critical information security is to the businesses that deal in it, and how a flaw in their security can make companies vanish overnight. It really provides some darwinian pressure to get security right!
Short the exchange rate + significant DDOS attack on the exchanges = millions in free money. That's just a for example. It doesn't even require explicit crime on the bitcoins themselves, and can be done at a safe remove through multiple cutouts. (Historical point of comparison - shell companies were used to short airline stock just before 9/11, resulting in tremendous windfall profits for presumably close allies of the perpetrators)
You could make similar arguments about security on the internet compared to physical security in the real world. The recent Target credit card theft, for instance - it's unlikely that the thieves could have appropriated 40 million credit card numbers by physically taking them!
> Short the exchange rate + significant DDOS attack on the exchanges = millions in free money. That's just a for example. It doesn't even require explicit crime on the bitcoins themselves, and can be done at a safe remove through multiple cutouts.
Sure, but you could achieve a similar effect by attacking an internet retailer and shorting their stock. It's also a lot easier to short stock, which is a shame, as shorting typically reduces price volatility.
Irreversible, unregulated, software-driven money at the consumer level is a thief's wet dream. It's even more appealing than cash. Money can be stolen from halfway across the globe, anonymously. Digital currencies face security challenges that go far beyond those of the fiat currency so many people despise.
Besides the theft problem, there's the crime problem. Digital currency is extremely convenient for high-dollar criminals like international drug and arms dealers. They're the first big customers, while mainstream businesses lag far, far behind in their own cautious way. This makes governments even more hostile, and civilians as well. And a currency that isn't accepted by the vast majority of legitimate businesses is not terribly useful.
But to your other point... yeah, banking software is not necessarily a paragon of security, any more than any other big enterprise software. But consumer-facing parts are generally fairly limited in scope (worst breach I know of is the recent Target breach), and the really big-money parts are hidden well away from the world and buried under many layers of process as well as software security.