Every government  be it military or democratic enjoys monopoly of control of both economic and political affairs in their territory and they feel threatened when any system comes in that takes them out of control and regulations keeping them oblivious of it's operations.  Apart from that even countries that have it in mind to adopt cryptocurrency as a legal tender finds it difficult to do so due to the volatility of the currency and unlike paper money there might be incongruent match in the price of commodities with the value of the cryptocurrency.

For example, we all aware that within a split seconds the value of a coin can fall very low and in the next minutes rise and fall below average, now how do the average market woman across the street manage to align this together. No doubt cryptocurrency is a great way out of so much interference by the government into private financial life of people and adopting it won't be a bad idea but there are issues that need be attended to in adopting it.