But the problem with US regulators is that they think the bitcoin has a bad effect specially if being used underground specially criminally
It's not only about what would they think. It's also about the fact that "lobby" works pretty good in US and I expect that the anti-Bitcoin banks are still more powerful than the pro-Bitcoin startups.
But, thanks to Japan, I'm confident that in a not-so-far future US will have to make their move, because one factor of rising importance is the fear of falling behind.