this is like "collector items", not currency. A very scare "resource", if you can call it that.
Having a finite amount of currency is important, because it means that money will not be able to be printed! Therefore, nobody can mess around with how much things are worth, and where money exists (like a government). Just as there is a finite amount of gold in the world, there will be a finite amount of bitcoins. You can divide them ever-smaller though, which will give us a nice steady inflation. The current software divides them into cents, but we can go as far as we need in the future.
the purpose of currency is not to hoard it - it is to spend it for goods/services.
This currency is not being made to be hoarded (and not being hoarded when it is being made), which is proven by the fact that people are selling goods and services (and others buying them) for bitcoins.
FIAT currency tends to be *backed* by something, like an economy, like USA or European Union or even China. What is this backed by?
Bitcoins are being backed by the price of the electricity that it takes to generate bitcoins. Soon, (maybe even right now, I'm not too sure) the price of generating a bitcoin in electricity will the same as the value of a coin. So unless computers get a very sudden leap in efficiency, the system will work just fine.
Anyway, another fad "currency". Might as well collect "ISK in eveonline" or "gold nuggets in WoW" - same thing.
Parity with USD is not a fad, it shows that popularity is growing. This parity is a result of market demand, not from someone randomly saying that it is worth that much.
I encourage everyone to do their own research about the nature of bitcoins, and of currency in general.