It's because central bank are know how much bitcoin can help the people and the country economic, but i didn't understand why they didn't allowing full adoption of bitcoin operation as legal currency, one thing i senn the reason is because bitcoin is threat currency to become banks are die.
Maybe central banks still seeing some holes in regulating the cryptocurrency and adopting it fully. I think they are weighing the pors and cons of cryptocurrency in their and in society. Bitcoin is allowed to continue because even governments see some potential in here and benefits for the mankind.