But if the overwhelming majority of US citizens do in fact believe that the actions of the bank executives should be illegal, the logical thing to do would be to change the laws. (Of course, this solution is a bit unsatisfying, since no one can accurately predict these major market collapses and the next major crisis will likely be different enough that it could very well fall outside scope of any new laws.)
Sidenote: Unfortunately, the recent conviction of Raj Rajaratnam will probably assuage public anger while not at all addressing this issue. From what I understand, he was found guilty of insider trading, which is more or less unrelated to the mortgage-bubble/financial-crisis.