Its not the morality but the expectation of the housing prices bouncing back to normal like the rest of the economy that is keeping them from walking away.

But the issue with realestate is that its not as agile a market as stocks or commodities. the volatility observed in a month in the stock market is probably going to be observed in a year in real estate market. And I am not not even talking about the phase lag but the different scales of variation between the 2 types of markets.