Imagine that some respectable country would go far beyond legalizing cryptocurrency and start one of its own. It would surely be no scam and it would probably have a strong support, but would there be any drawbacks to the currency and the state itself? Would it get more attention than some of the biggest coins now?
It depends on which government issued it and its motive on issuing it in the first place.
One drawback i could think of is that coins issued by the government is most likely politically driven. Meaning, its aim isnt to offer a decentralized solution, but maybe it's just more ways getting away with corruption.