Well, you're blaming the bank for using your money to make a profit? So I want to ask, do they force you to give them money? Or do you voluntarily and agree to give them the money to get that small profit back? They are just a business, and they need profits to survive, if you know that they are taking advantage of you, stop using their services.
In this context I don't want to blame them, as long as they can still be trusted then go ahead. In terms of actual profits, it is not that big for me personally if I use them as a place to store fiat money. Just a few percent interest which in my opinion will not be balanced with the return when Bitcoin passes the purchase price in a matter of years.
I haven't had any fiat currency balance in my account except for a few for daily needs when my savings at home are empty.