Put your self in the shoes of a person responsible to "control" financial things in your country then the answer becomes more clearer.
Bad points ( financial )
- high volatility makes them good way to make money ( too much money which is unaccounted for )
- it cannot be in a controlled environment.

Social points
-Increase in monetary gap of society
- normally money is inter convertible with power ( some countries ) hence can cause disturbances.

of course bit coins has much good points but unless the negative points cannot be countered it seems dangerous and it is banned.
even we must see the countries banning it so reasons can be even more clearer.