To be truly decentralized you need something like "digital cash", but nobody's been able to come up with a good way of implementing that, yet. Also, I'm not sure people are prepared to mix the problems of cash and electronic transactions just yet, there are some advantages to the banking system we have now, such as the ability to reverse fraudulent transactions.

I think the example from fiction, Cryptonomicon, is actually very helpful, because they understood they needed a big honking pile of gold to kick-start the legitimacy of the whole thing, if it's just free floating then it too easily becomes a pyramid scheme and you have people who just do currency exchanges but who never actually use the new currency as money. You want people to hold onto money because it's money, not because they think the money can go up in value, that's precisely what you don't want.

Unfortunately, there are now a lot of people in the bitcoin world who do what the exchange rate of bitcoins to go up, because they view bitcoin's as an investment and they still view dollars as "real money". And in most ways they aren't wrong. But they're also making it harder for anyone else to use bitcoins just as money.