This is still a question nowadays because not all country gives a go signal for bitcoin. They are taking a lot of things just to slow down the growth of this currency. If not eliminate the whole system. What can you say guys.
There are a lot of things to consider when legalising a something that cannot be regulated by the government. Have you heard of the 'silk road case' wherein people used bitcoin as a gateway under the dark web for acquiring illegal goods? Due to bitcoin's decentralised nature, anonymity in transactions is inherent. The government fears that it might be abused and gradually contribute to their criminal rate.
As for the economic aspect, personally I see it as boon rather than a bane. I do not understand on why the government prohibits bitcoin when it can actually support individuals of all aspects in terms of acquiring alternative income.