I don't think that lack of definition will remain forever though. As Bitcoin gets larger it will be increasingly difficult for governments to simply pretend it away. Governments around the world will define Bitcoin because that is the first step in regulating it.
This will be incredibly difficult to do because it will be
like regulating air guitars. Any statute trying to define a 'bitcoin' would easily
void for vagueness and rule of lenity. I would hate to be a prosecuting attorney because any statute crafted would look like swiss cheese with holes large enough for the other advocate to drive an 18 wheeler through.
Well that is certainly your opinion and if true then no Bitcoin related business will ever be regulated. I however don't share that optimism. It may be a while but governments will attempt to at least control the edges of the Bitcoin economy (brokers, exchanges, major merchants accepting Bitcoins, etc). The air guitar concept could apply to a lot of intangible things (insurance, gambling, investments, money transfer, etc) and the lack of tangibility hasn't stopped governments from regulating and controlling. That is what governments do. They control. That is all they do. They always seek to control. You can't do that without definition. Still I hope I am wrong and will be pleasantly surprised if I am but I seriously doubt I am.
I would point out even your link seems to express the same idea
Of course, this will adjust over time as more and more bitcoin value can remain in the bitcoin ecosystem for necessary daily transactions. But in the meantime, regulation is increasingly possible in this area due to exchanges requiring a certain degree of jurisdictional presence and centralization. As with buying and selling air guitars on eBay, regulators can exert influence because there is a centralized point of exchange. It matters not what is being exchanged.
Entities like Tangible Cryptography which interface between the Bitcoin world and traditional fiat currency world will probably be subject to more regulation in the future. It is what governments do.