Those countries that are banning bitcoins sees that it is just a tool for illegal transactions because they are not looking at its beautiful characteristics that it can be useful and helpful with the governments economy. And for those who are unbanning bitcoins, they just realized that the qualities that bitcoins have will give benefits to them.
I think only a few countries that they are allowed to use Bitcoin. I don't know what revenue that country government is getting from Bitcoin transaction. The main reason why bitcoin is not accepting in all country means they will not get any income from this bitcoin transaction that is why this Bitcoin is banned in many countries.