Bitcoins is not yet a legal currency cause not all countries, world bodies have accepted or recognise it. You wrote so much and how come you fail to understand that this coin cannot be controlled by anyone, no one can manipulate it and most of all governments cannot find out who owns it or make you pay taxes. There is a huge hassle process and it's expensive to track it, make a whole set of laws. You get the point don't you.
This is because politicians are concerned more about their own interests than the benefits offered by crypto. With time, it will get unstoppable though.