The only relevant reason I can see to using the bank is interest. But then again...its still very pointless, unless you had some sort of battle system were you could lose money not in the bank (by being attacked for example). Otherwise, members would just leave all their money in the bank, and when they wan't to buy something they withdraw it, but are gaining interest while their money is in the bank. If this is the case, why not just create a hack that increases a persons money depending on the amount they have, no point for a bank....right?