The global economy is nearly 80 trillion USD per year. Payments using any type of cryptocurrency as a medium of payment is a tiny fraction of this total.
What are some of the reasons preventing cryptocurrency from being more successful as a medium of payment?
Not every country can actually manage to have a good economy and that is the reason why cryptocurrency will not always grow because it also requires a legalization from the government.
I'm not aware of any jurisdiction that has prohibited using cryptocurrency for payments. Some have banned ICOs and other security related uses cryptocurrency. So, I'm skeptical that prohibition is an obstacle.
I'm also not aware of any jurisdiction that enthusiastically supports a cryptocurrency. Until there is a cryptocurrency that helps governments apply regulations, I doubt there will be such support.
What needs to happen is a collaboration between cryptocurrency designers and regulators.