Honestly, if your one of the many people that got a mortgage you couldn't afford, I'm glad it failed. It's a lesson well learned. Our country already lives well beyond its means. Hopefully this will open many peoples eyes about their money.
There is one problem with "let them fail!"
When millions of them fail, banks fail.
When banks fail, the dollar weakens (loses value) significantly. If it weakens enough, other nations stop trading in it (accepting it) and the US goes bankrupt.
it happened to Russia in 95 and Mexico in 1998. People starve, there is chaos, and they start over.
So yes, it's a bad idea to let millions of people falter on their loans. Those banks keep our economy alive.