I really don't know how they legalize or i-legalize such thing as bitcoin because you are using it with your own internet and computer hardware maybe they just not supporting it before but every citizen of India can use it no matter what happens unless their government issue a criminal liabilities in using bitcoin.
If we would used Bitcoin in terms of transaction and investments it is true that it is much easier to used compare to fiat because it has the capability to deal with transaction and it could be used in different form just like in investments that could give people a profit without dealing with tax. It is a good thing becasue it can be used by all forms of people regardless of their identity or transaction reason.