Reason is simple, when our government looks at bitcoins, they are incapable of tracing any person or
company holding responsibility for Bitcoin not only in their jurisdiction, but in the entire planet!

Legal Implication : In order to recognise any medium as authorised payment and settlement system,
 they should have proper licences from Reserve/Central Bank of the respective country.
So that government can ensure all the preventive measures against fraud , money laundering and any antisocial activity .

When a case is filed against Bitcoin, not the people transacting bitcoins, inside the jurisdiction,
 governments cannot be able to perform their legal obligation to the society !

This is the first part that makes the government to take hostile approach to crypto-currency.