China is becoming powerful and is excelling a lot in so many other fields as well. China knows the worth and importance of bitcoin in a very well manner. So this is just their own move in order to take control of bitcoin. Since china’s plan has flopped quite badly, so I think there is no other reason of banning the use of bitcoin in their country.
I don't really think their plan was to take control of bitcoin, or to buy bitcoin at a cheap price or any of those things. They're government is well known for it's tight control over things, and bans are common there. They've banned facebook, they've banned movies like Avatar, or even celebrities like Brad Pitt. These moves where just to control their population, and the ban on ICOs and exchanges is to keep control on what they value most, that is their money. They really don't want to allow their money to exit the country, and exchanges and ICOs where doing just that. If they find a way to regulate crypto, they will allow it, if they don't, then they will ban it.
The problem is that they are probably already realizing that bitcoin is different, and can't really be banned. If it could, they would have made it illegal already. That's why I think all this is temporary, and they will just regulate crypto. Not because they like it, but because they know that if they ban it all together, it will just be used underground, and it will be much harder for them to prevent money from leaving the country.