There were several attempts, actually, and they all came to the same bad end. Tightening up the regulations ends up tightening lending at the margins, ie, poorer or riskier people. The bills went nowhere because the line of attack prepared against the bill was that the people for the changes were evil bastards preventing honest, hard working poor people from getting homes and pursuing the American Dream. Supporters of reform resigned themselves to defeat because:
(1) That line of argument is more convincing than a long-winded tale of leverage ratios, bond markets, and chaos on Wall Street at some undetermined point years in the future.
(2) If they showed courage and fixed it anyways, they'd instantly create a winning issue for their opponents, who would then proceed to undo the new regulations and pat themselves on the back about how nice they were to the poor.
So, no, it's not realistic to have regulations pass. This is one of those cases where the general will among the electorate to fix the problem will only occur in reaction to a crisis.
For a better example, imagine for a minute that the Republicans had rammed through a spiffy new airport security bill in early 2001, and the terrorists ditched their plans for 9/11 because of greater security. Would the Republicans get credit for preventing the death of thousands, or blame for 'unnecessary inconveniences to travelers'?