The economic assumptions underpinning the Bitcoin ecosystem are laughable, and ignore hundreds of years of accumulated understanding of how currencies work with each other.
Paper money is about 100 years old. That's it.
The only thing about "paper money" that I can think of that is about 100 years old is the beginning of the departure from the gold standard (http://en.wikipedia.org/wiki/Gold_standard).
... why would it be true for economic practices? Some experimentation is good, without it there would never be any progress at all.
Appeal to authority based on the age of ideas is something you can only get away with in religion, astrology, and it seems, economic 'science'.
Sure, there is a large chance that new ideas might fail but you can't simply argue against them because they go against old ideas.