I don't understand the idea of bitcoin bank who will hold the funds which is totally against the spirit of bitcoin, everybody love bitcoin because of freedom so that I'm against this idea, very hard to understand why would we give our coins to 3rd party without any security about our funds, investment in bitcoin is better than this idea.
You have the point and i think we have already use the wallet as our bank.. and i think we dont need bitcoin bank except for ATM or any bitcoin machine that can withdraw and deposit bitcoin instantly.. will be a good idea to spread worldwide than bitcoin banks..
We are using it anonymously so if there is bitcoin bank i think they need our identity in order to be member of that bank..
The difference is that you may get a loan or get interest with banks as well which our bitcoin wallets cant provide. Bitcoin Bank is against the basic concepts of bitcoin but that is what people want the bank to be I assume. When bitcoin hits main stream of adoptions, people may start forgetting to demand for bitcoin banks.