But other than gaining interests from bank, I am not finding any big advantages of using bank accounts to have our wealth with them. In this modern era, we are all thinking about having secured and fully privacy assure way of financial system so that we can safeguard ourselves from robber, for example.
You talk about safeguarding from robbers but that is exactly what banks offer. Even if due to your own negligence someone fraudulently gets money from your account the bank will refund you. There is no digital currency that protects your money better than that.
The main advantage is obviously privacy though, banks do not really offer any form of privacy.