Haven't you just described what Coinbase is trying to do? Become a bank?
Only they are starting with the cryptocurrency wallets and will likely add current accounts and loans later, after they've floated on the stock market and raised a lot of capital.
I'm surprised the existing banking system can't see what is coming.
they most probably see it that is why they are trying to fight it instead.
because they know that those who want to use cryptocurrencies such as bitcoin which are decentralized are using them because they are decentralized and because they don't need a bank for that matter. these people will never use "banks for crypto" no matter what they offer. and in the long run we will have more of this group. so offering such services may not be so profitable for them.