I think you assume, and rightfully so based on how people discuss this topic, that 'afford' is a black and white numbers game when it comes to mortgages. It's not. I can clearly 'afford' a home mortgage worth the amount I spend in rent each month, but I cannot get a mortgage for that right now. So really the discussion is/was/should be about easing the mortgage qualifications and restrictions. It was not as if people were giving mortgages for million dollar homes to minimum wage workers, and no one would sanely suggest that is a good idea.

The other side is renting -- where the landlord can raise rents to almost any arbitrary level (well to the market rate, but if you're not making bank it might as well be arbitrary). My understanding is 5-year ARMs where also subject to the whims of the bond market (LIBOR or whatever), so really the difference between renting and mortgaging in this case are just semantics.