Of course we already know the motive, what else if not money laundering, what else besides that? because we ourselves know that bitcoin transactions remain anonymous even though they are transparent. No one knows your bitcoin address, nobody knows how many bitcoin addresses you have. so why are you looking for other methods to be more untraceable transaction, if not for that activity. Even so, the rules will depend on the laws of each country right?
I still cannot know the reason for it too really, and left to me, I think if the government wants to start any regulation, this should be the first focus, they need to ban it first, because this system is a scam system to me, and if we really reason it well, based on what you said, bitcoin is already anonymous and I dont see any reason for more deep anonymity if it is not for ulterior motives of the provider to use it for scam purpose.
This was how binance actually could not trace their hacker, and even so many people have used it for money laundering that would make it not traceable. If the activities of people using it become rampant, government might really have to go after it as I don't even see any effect of it on the market. It is not helping coins appreciate but rather tarnishing the image of cryptocurrency.