Bank normally is supposed to help people whenever they are in need of cash but nowadays reverse is the case, I don't know if I will say it is because of the government and currently bank charges is becoming something else, whether you do transaction or not they will charge you. Below is the reason I prefer saving in exchange to Bank
Whatever reasons you might wanna give to make CEX more attractive to traditional banking it will still make them of no difference in operations because they both work under the regulations of the authorities and can confiscate or withhold our funds at the demand of the authority. CEX just like traditional bank can be hacked or an insider robbing off the CEX leaving customers at the risk of losing their funds.
Nothing different between the two financial institutions except that one is dealing with fiat while the other is on cryptocurrencies. Not your keys not money wasn't is a popular phrase for a reason!