Really interesting piece.
I am amazed at how often I find people that believe that paying a mortgage on a house that costs more than they owe is a moral imperative, or simpy as 'the right thing to do'.
Why would you keep a promise to bank that would not do the same unto you? If you continue to pay on a house that is worth far less than your mortgage, you are giving the bank money to cover the mistake it made on you, while to a large extent, the bank has already been covered by tax dollars for that mistake. And, all the while, you are investing less in your retirement or other aspects of your life, making your total loss much larger than just the difference in your mortgage and the price of your house. Your mortgage was a deal made in a bubble. Both sides were wrong. Why should the banks get an out where homeowners don't? Walk away. Invest in your future.