The kind of people we have in government are people who always want to fight for their selfish interests, anything that will surely benefit them. If it's something good that has to with better development for humanity as far as it won't benefit them they will surely go against it.
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.
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.
That's not quite correct, in my opinion, in the sense that the finance industry successfully lobbies to create incentives against decentralised financial tools, which otherwise they want to continue to provide and control, at a premium. I've been on the lobbying side, and in my experience it is laughably easy to convince officials to see the light, usually because of very human insecurity and reverence issues, rather than outright bribes.
The other and major part of governmental non-acceptance is, I believe, precisely the decentralised qualities; every government's first and foremost issue is the successful taxation of its constituents, and in a fully decentralised financial system neither verification nor enforcability are feasible.