who says you should put "all" your bitcoin in a bank? the problem with some of the posts here are they are too skeptic about banks, banks can be a useful proof that bitcoin will be legal if banks will accept bitcoin deposits, look at the bright side people, there are doubts all over the world whether bitcoin can be really useful for buying, trading and selling. these news about putting up a banks will certainly erase some of those doubts.
even with fiats or paper money, you should not deposit all your money in banks. the idea was to make cryptocurrencies circulate like ordinary fiats.
You're right, too skeptic about banks, but there's a reason for it. Banks usually act in the most profitable way for themselves. If lots of people store their bitcoins in a bank in future, then the price could be so easily manipulated, as well as banks can now manipulate gold price and deceive people. That's why cryptocurrencies must stay decentralized.