Licenses and certifications do not really mean squat. Remember back in the day when everyone got the MSCE or MSCA for windows 2000 and you could get it by studying a mail order book and passing 3 or 4 tests without ever having any working knowledge outside the books and the limited test software that came with it. Well, if you don't, it meant that a lot of people sporting a lot of qualifications were almost completely clueless when they had to do something that wasn't spelled out exactly like the book. That was a lot of things in normal working life.
Right now, I can go to the mayors office and pay a $125 fee without taking any tests and become a licensed sign installer in my town (well, it would take a little more then that, but I would be licensed without showing any aptitude or ability).
As for the sub prime mess, nothing was wrong with sub prime lending. It goes on every day and is a valid part of the financial sector. No amount of qualifications to a banker would change that. The problem with them were actual fraud perpetrated by some lenders in which they didn't care if the loans were ever paid back as long as they were being paid until they could sell them off buried inside some mortgage-backed security. A lot of lenders were prosecuted because of that and I mean people actually making loans, not just companies they worked for or with. No certification is going to remove outright fraud.