Stronger regulators alone are not enough. The only safe guard that really can be effective to prevent yet another banking crash are banks that cannot depend on the government for support.
This by definition requires smaller banks.
A monopoly distorts the market by power of pricing what it monopolizes. A bank which is too big to fail and knows the government must bail it out distorts the market as well. It is able to take on risks that smaller competitors cannot.
Everyone outside of the banking sector is likely to support separating investment and risky banking from traditional banking. Most would favor breaking up any entity they might have to pay to save.