I think the governments do not want the BTC to affect their economies. I think because they have not seen the real value that Bitcoin can bring to the economy of their country.
Each country has a different policy, in some countries bitcoin is legalized but there are also those that prohibit the use of bitcoin in their country. The goal is to protect its citizens from the bad side of bitcoin. As a bitcoin digital currency is clearly not wrong, the wrong is people who see a gap to misuse the system in bitcoin trading and cheat or do illegal business. That is what the government feared.