The main reason behind not accepting Bitcoin is because Govt will not be able to see the actual portfolio of any citizens and they will not be able to charge tax. Bitcoin is decentralized and it's cannot be controlled by government. Central Bank are the main opposition of Bitcoin in any country. If people start to make invest in Bitcoin then They will withdraw money from the bank and no government want this.
they can't do anymore some of their illegal things once they start to use Bitcoin.
Actually, is this, Bitcoin as transparent yet privacy-friendly system undermines two of the more complex and vital activities of any government, taxing its citizens and keeping secret some of their expenditure (for both legitimate and no-so-legitimate reasons). It would be actually good for civilian society, it will increase accountability and give citizens a solid bargain chip against government, as people will make public more of their economic activities (and pay more taxes) the more they are satisfied with the government
The reason government won't accept bitcoin is not because it is a decentralized currency, it is because they won't be able to print it like they print fiat to steal as much as they can .
If bitcoin is something the government can manipulate to steal public fund they would accept it even before now without any delay.
This one is actually a mixed bag. The lose of control may look bad for a specific government, but when you take into account that every other government will lose control too it may become the "less bad" international arrangement, as nobody will have enough control over international finances to use it as a weapon, it may even incentivize economically weak states to accept Bitcoin. Overall it may be a main reason for the likes of USA or China, since they use international commerce and finaces as political tools, but will be a secondary issue for small states
And a small extra:
At least for western democraties, that's a dire view of elected officials. Perhaps Plato put it in a more balanced way in The Republic (mother of said western democracy), to the effect that the best suited to rule are least likely to want to, and perhaps those less suited to rule will be more inclined to desire power due to their own shortcomings.
It may look as a dire view, but all (non totalitarian) western political theory since the end of Napoleonic wars acknowledge both the state and its officials as selfish agents whit their own goals different to those of civilian society, but that is a theme for other boards