Do you fault Fannie and Freddie as a government sponsored perverse incentive since they effectively put the government guarantee on all the MBSs? Or all of the policies pushing for home ownership?
That the tax-payers should eat the losses is a sad result of the banks (and other writers of high risk mortgages) creating a problem.
There was a very general lack of adequate regulation under GWB.* It was the philosophy of his administration (and of Ayn Rand taught Greenspan too) that the government which in interferes least with the private market place is the best government. Unfortunately, this POV is common among many Republicans and nearly all tea-party people. If anything that "small government is best" POV seems too be growing. For example, many are happy that the new Congress will be unable to act to solve problems.
Greed can be a good thing but unregulated it leads to economic disasters such as we have now.
*During the Congressional investigation of the Madoff mess, the former head of the SEC explained that part of the reason why they did nothing even when provide with very detailed evidence that Maddoff was running a Ponzi scheme, said "The administration keep us on a very tight leash."
To more directly answer you:
Yes there has been for decades the idea that home ownership should be encouraged. That renters are less responsible citizens, etc. It is built into the tax laws that you can deduct the interest on your home mortgages. These complex tax laws are really an economic distortion force of a central planning government - but few understand that. The USA has about the same, but hidden, central planning via the tax laws as the old USSR had openly, IMHO. I.e. practically every economic decision in the US is strongly influenced by the tax consequences of it vs. its alternative (renting vs owning being an obvious example. SUV gas hog vs European style cars is another important example of US's low taxes on gasoline. Oil depletion allowance tax breaks another, etc. the list is endless.)
Fanny May & Freddy Mac (or some thing like them) is essential to keep mortgage money available. The banks (and other writers of mortgages) must have some way to sell the mortgage they write or soon they would just shut down their lending departments. What is wrong is that they need not keep any "skin in the game" so don't need to be prudent about what loans they write. Furthermore, the sold mortgage were resold many times, to other buyers paying with mainly borrowed money. (They had little of their own skin in the game too.) Packages of packages were created, for more diversification This multiple reselling and re packaging built the leverage to 30 fold or more. Thus even a 4% reduction in home values wiped out 100% of their value. Made the MBS packages into toxic trash. Most falsely assumed that home prices could only go up so high leverage was wise and profitable.
The Bush administration's SEC, etc. and Greenspan simply and falsely assumed that the free market would self regulate and be prudent. Part of the reason why I could predict, and post here, that a run on the dollar (and subsequent depression), coming before Halloween 2014 was inevitable while GWB still had more than a year remaining as POTUS.