With all these advantages about bitcoin, i don't see enough reason why the government is still hesitant to accept bitcoin knowing all its transactions are transparent and so you can't see any illegalities from it. Best proof is that FBI has managed to traced whatever fraudulence that happened to it. That is, if the government can also be transparent in all their transactions, so there is no valid reason that bitcoin cannot be accepted as a currency.
The government is still hesitant not because of transparency but because it is decentralized and they could never get a hold of the whole picture of all the btc transactions. I believe that's one major reason. But when we talk about transparency purposes, btc is actually a good currency as the people will now see where the money goes. For example, government projects with known btc address/es, the public can now trace where the funds are going, thus, lessening the bribery part. That is, if the government will utilize the btc option.