Glass Steagall prevented the concept of too big to fail. It was a good thing. Removing it was the banksters dream and laid the groundwork for the subprime crash where the investment side of banks were pushing the consumer side to give out crap loans they knew could never be serviced.
And this also opened the door for the haircut concept. Investment banking was never considered too big to fail before this.
I agree G/S was a good thing, but Long-Term Capital Management