Hard to understand how some $600-800 billion of potentially bad mortgages brought the global financial system to its knees. Looking at all of the government interventions around the world, in hindsight, I think we may find that it would have been better for the U.S. government to simply buy all the distressed housing stock in this country and use it for a massive program to turn lower income people into homeowners (or keep them in the homes they already have but can’t now afford). At least this would be more transparent than the current funding for ACORN type outfits, mandates to banks to lend more (lower their credit underwriting standards) to lower income segments, and Congress pushing Fan and Fred to buy up the loans so originated. Set an arbitrary income threshhold so that people of means who upgraded beyond such means suffer the consequences (like the CFO in the recent WSJ article who bought a $2.5MM home on a $250K salary and then lost his job, the house and everything else - idiot).
Anyway, the root causes are government policies that try to defy economic law, and a securitization system that separated risk from reward. Kill Fan and Fred and any such GSE - replace it with an explicit welfare program such as I outline above if you like and simply must have government involvement in the mortgage business as a matter of social policy (and if the taxpayers will still agree to this) - and get back to some form of portfolio lending, which would maintain some prudence in loan underwriting standards.