That's good news as the adoption rate will increase but this step might not be liked by the enthusiasts of decentralization (E.D.). I mean to say, that banks are centralized and they offer BTC trading, which is totally the opposite of decentralization. That's why I said E.D. might not like this step. But there will be 2 types of people in the world. Like if there is bad then there is good.

This means, overall the adoption of BTC will increase and that's good for the BTC price. And you asking why BTC is being adopted by the banks? I say they don't want to be left behind just like the post office has lost traffic due to email and mobile phone networks. They don't want people to move on to crypto/BTC. That's why they are adopting BTC but those who will use their products have to follow their rules. And one more thing we all should keep in mind is that, "If you don't own the key, then you don't own the assets".