Sad to say, such people are at higher risk of default at some point. I would be concerned these policies will simply set us up for another mortgage crisis down the road.
On the other hand you get the people who think they're smart enough to game the system. They want to borrow all of the money they can because they can borrow it for 4% and they can make 5 1/2% leaving their money in the market. And they want to buy the biggest house they can, even if it means an interest only loan. Because they're gonna make 50k in the next 2 years on that house. To smart to be dumb. Just plain stupid.