It doesn't contradict. In my ideal libertarian world, there wouldn't be the current statist quo to worry about. In the world we live in, there is, hence I think registration/licensing will be needed to expand beyond tech savvy people.
Thanks a lot for the info about your exchange. It makes a lot of sense. However, I remember MtGox having a bank account in France (and AFAIK a license in Japan). So MtGox is doing illegal stuff?
I'm going to talk with an international fiscalist in the coming weeks (next week a local Belgian one, later an international one). Maybe the exchange can be run from a VAT and tax free paradise somewhere (Belize, Antigua, ...)