Even if they were the most ethical by most standards, the idea that currencies should be monopolized by the state and controlled is dangerous. It's not that the people in charge have to necessarily be malicious for things to go bad, it's that the action of controlling money itself is almost impossible to do well (if possible at all).

The idea of imposing restrictions on alternative currencies is also an inherently wrong thing. I still don't understand how America has come to the conclusion that spending my Bitcoin should incur capital gains tax.