Yes, 70% looks much, but in absolute numbers it's a very small number actually. It's nothing that can justify a 300% price increase. The "boom" in Japan happened mostly at the exchanges like bitFlyer, but that is not sustainable Bitcoin real-world usage but speculation.
Mmh ... where do you see that? In media and real life I had this feeling in 2013 when there were a lot more people interested in Bitcoin than now, I think. The "buzz" was much stronger then. There were lots of shops starting to accept Bitcoin this year, and 2014. Most have ceased to do so, some new ones have appeared, but growth seems slow. It's not that I don't see some growth - mainly in "non-traditional" countries. But again, nothing that justifies a 300% increase in half a year.
Just curiosity: What would this "detaxing" mean in this context? Do the US have a tax for simple monetary transactions, or would this mean people would not have to pay VAT if they pay with BTC?
Unfortunately, I'm 99% sure that you are wrong.