Comment: Breach of contract

Not paying your mortgage is just a breach of contract. Nothing immoral about breach of contract. It is a business decision and the law provides a remedy to the injured party. In fact, there is a whole philosophical defense of breach of contract called "efficient breach" which says that not only is it not immoral to breach a contract when it doesn't make econimic sense anymore, it is beneficial for society as a whole for you to do so.

The one fly in the ointment is that anti-deficiency laws and bankruptcy laws make it impossible for the lender to get a remedy. But I say to hell with those crooks.