Some of it is the fact that the people in charge dont understand it, but the other part of the reason is because world leaders are afraid cryptocurrencys will overtake their own country's currency in which case, they would have no control of where the peoples money goes. In my opinion, crypto should be available to everyone around the globe. 
One thing that is good for the government of most countries in the world today is starting to open the door to legalizing bitcoin as a regulated asset. Although the legalization that the government is considering will increase public interest in bitcoin, the government will not give freedom without control to its users in their country. Although it is not allowed to use it as a legal tender, personally I am happy with this friendly regulation because I think it will also have a positive impact on support for bitcoin.But maybe government regulation will change over time and we should hope that bitcoin is legalized as legal tender. The future of bitcoin is still quite potential and it will continue to grow. The government doesn't seem to want to take hasty steps in making a decision because they need a lot of testing and research on how positive the economy is of a country that legalizes bitcoin as a mean of payment, imo.