"The repeal of provisions of the Glass–Steagall Act by the Gramm–Leach–Bliley Act in 1999 effectively removed the separation that previously existed between investment banking which issued securities and commercial banks which accepted deposits. The deregulation also removed conflict of interest prohibitions between investment bankers serving as officers of commercial banks. This repeal may have contributed to the severity of the financial crisis of 2007–2011 by allowing banks to become so large, complex, and intertwined that both they and their regulators failed to see the systemic risk that a failure in one part of one bank could lead to cascading failures across the global financial system."
That was a pretty significant act of deregulation.
As for the amount of regulation, it's online: http://www.federalreserve.gov/bankinforeg/reglisting.htm
The complexity of the regs has more to do with the creativity of people trying to get around them than the enthusiasm of regulators. The image of a gimlet-eyed little man churning out page after page of obfuscated prose that serves only to hobble industry is amusing but inaccurate. As we saw in the Gulf of Mexico last year with the notion of "regulatory capture" the regulators might be hard to tell from the those being regulated.+Tim O'Reilly
The problem I see with measuring outcome, rather than regulating process, is that it starts to look like centralized planning. And there's an old saying about the end and the means…
Regulating processes — health and food safety regulations, conflict of interest prohibitions — don't prevent innovation, though they may force people to think a bit harder. But outcomes have to be looked at as well, especially in consumer products. No amount of process-oriented regulation would have improved the design of the Ford Pinto: for that, we have crash tests (which automakers could have decided to do on their own, rather than being forced).
It's really all down to greed and hubris. I don't know that the big banks were just scraping by prior to 1999. They really didn't need to be taken off their leash. And they gamed the politicians, as happens too often. Some promises of a bigger pie (and larger tax receipts) with assurances that there would be no cheating, those old rules were no longer necessary, and that was that.