A New Glass-Steagall?

In an emerging era of regulation reform, talk of new Glass-Steagall Act is going to be muted. I suggest that this is the perfect time to process the regulatory failure that produced the Great Recession of 2007-2008 into reasonable restraints upon our most important financial institution, banks. I further suggest that a blanket separation of investment and commercial banking is, as former President Clinton said, not appropriate. The problem is too complex for simple solutions.
Banks exist to supply liquidity for fluctuating capitalist economies. In order to do that they must make money doing it. That is a hard fact of capitalist life. There is nothing in this scenario to deny them the right to take reasonable risks in equity markets in order to increase their return on investment. The problem lies in the phrase, 'reasonable risk', and how that can be regulated.
I am here arguing that there is a solution to that problem and it lies in regulating mathematical risk models which guide institutional investment. Risk models must be demonstrably and categorically shown to be reliable in a hostile critical environment before they can be employed in actual investment strategies. That is not a simple solution but it is not a simple problem.
The legislation can be written. I suggest it be considered.