I am not able to figure out what is the point and role for banks to exist in a cypto society.
Depends which bank role you mean. Some will offer to safeguard your bitcoins so you don't have to. Some will offer payment automated payment services from your deposited Bitcoin. Some will offer loans, mortgages? Some will offer investments, others wealth planning. Some will provide loans for business and capitial infrastructure investment. Some will offer services to simply arrange those with money to provide it to those that need money.
So, pretty much the same as they do now. I wonder from thread like this how many people really get what banks do.