Well, wasn't "common sense" his campaign mantra, specifically in situations like these? :)
To be serious, the reason a fiscal conservative like me would support regulation in these instances, is because there is no personal negative reinforcement in the modern economic system to decisionmakers that give bad loans. By the time these borrowers default, the people undersigning the loans will be retired in Aruba and not give a sh*t. For that reason, banks will attempt to give bad loans using any possible loophole that the governemnt does not close up. Sad but true.
"The trouble with socialism is that eventually you run out of other people's money" -Margaret Thatcher