Yeah the fact that you cannot be traced via Bitcoin is making it the ideal place for online criminals. You will never be able to stop all criminals so just do not focus on them.
yeah it would greatly assist criminals in their illegal activities will not be easy in recognizable by making a payment or transaction with bitcoin. that's why government prohibit it
Yes It does help criminals, but it is not prohibited by the government in the United States, due to part that it was created by the people, and adopted by a large majority.
If it was ever prohibited it would be facing a serious financial problem due to the fact that Bitcoin is tied to so many areas of the economy already.