Precisely which regulation was undone to allow the crisis?
I think it was 1999 when clinton signed something that changed the restrictions on Fannie and Freddie, to allow those institutions to operate on a much wider cash to paper margin ... where it had been 10 to 1 it was opened up to like 30 to 1. A whole lot of subprime was then dumped into Fannie and Freddie bringing about the eventual collapse. All it took was for one or two large banks to fail, and upChuck Schumer saw to it that the dominoes started to fall (by creating a run on a major in trouble bank holding massive bad paper), perhaps hoping it would help Hillary in her contest with Obama. Who knows or will ever know, outside of secret bank examiners.
I don't know which rules were regulations and which ones were simply industry practice, but until recently it was necessary to have independent appraisers confirm housing values before loans could be written. That rule was changed to allow lenders to do their own appraisals.
Couple that change with 110% LTV teaser-rate mortgages and everyone involved in a house sale will want the price to be as high as possible. After all, why should the "buyer" settle for getting $10,000 cash for "buying" a $100,000 when he can get $40,000 cash if he agrees that the house is worth $400,000? If he's never going to pay anything beyond the teaser period, why should he object to the higher price?