Many people who use bitcoins want to control their own money only by themselves. But I think that such services will be demanded in the future. So people may want to keep their money in bitcoin banks
And what says Bitcoin's philosophy exactly?
And why should it be against Bitcoin banks precisely? I strongly suspect you don't know yourself what it hinges around. Anyway, if there is any, it should be about freedom, right? So how can you say that Bitcoin banks would be contrary to it if they remain on an equal playing ground with other market participants? I guess you can't have it both ways, i.e. first declare freedom and then prohibit banks from participating. Such approach has been given its own term, it is called hypocrisy