To a certain extent, I really don't care. However, I expect the line to be drawn at zero - once the company takes such risks that they can implode the system, it's time to look at how risk management should be monitored and regulated.
Wall Street did not create risk of bad loans --- the modification of Community Reinvestment Act in 1998 did. It mandated a progressively increasing number of bad loans to be issued. As a result homeonwership rate increased from a stable 65% to 69% --- that's loans to 12M Americans we are dealing with. Wall Street is like a car --- it drives you as directed but it does not tell you were to go. It accommodated the government (with securitization, etc) but it did not create the problem.
Finally, you hold a typical socialist belief that the regulators KNOW and we only need to employ them. They do not, and have a lesser chance of knowing that a decentralized (free-market) management of the economy.