Its the people with the money to lend who set the rules, and since that lending money has been coming from wall street- when the mortgage is packaged into a bond and sold- they decide, not a broker.
Actually, I think now people are still guessing what wall street will be willing to buy up. I would assume that whoever set the rules outlined in the original post thinks mortgages meeting those criteria will be sellable on wall street, but I don’t think anyone knows right now.
I think the real test of this housing market will be the next few months. How many buyers will this new criteria drive out of the market? How many people who need to refi will not be able to and will foreclose instead? These are the million (billion?) dollar questions.