If there is negative MARITAL equity, and marital assets to help cover the marital debt, why shouldn't the marital assets be required to be available to make the creditor whole? I am contantly amazed that it is ok to demand part of any POSITIVE assets, but remaining negative equity made the lender's problem. The parties divorce, SPLIT UP THEIR ACCOUNTS, then two or three years later, whomever kept the house wants a short sale with no deficiency and the lender to EAT THE LOSS, WHEN THERE HAD BEEN ASSETS TO COVER IT DURING THE MARRIAGE.
I wouldn't say that it NEVER happens, but it's very unusual in my experience.
I don't know the rationale, but I suspect that it's perceived that the current housing slump is temporary. At the time the home was purchased, the couple thought it was worth the asking price. Now, it isn't. At some time in the future, the price will presumably have recovered so that the home is in the black again. Thus, if one of the couple keeps the home, then the current shortfall is only temporary and does not constitute any loss of cash.
Forcing the leaving spouse to pay 1/2 of the underwater amount would amount to a windfall to the staying spouse after property values recover. Plus, of course, the fact that actually determining the amount that it's under water is difficult. Most homes that are under water had property values that changed quickly, and possibly fluctuated, so it's not easy. And many are only slightly under water, so the numbers are not often as large as the potential positive equity numbers.
Don't get me wrong - I see your point and it is valid. It's just that there is an argument to me made on the other side, as well. Plus, the fact that I have rarely seen the negative equity used in the calculations in my experience.