This is kind of a two-wrongs-make-a-right argument.  If you don't think it's right that a corporation weasels out of debts that it could and should pay, I don't see how you can justify it when an underwater homeowner does it.

Moreover, (and take this with a grain of salt, because I have not closely examined the AMR bankruptcy) I think the AMR bankruptcy is probably more defensible than a true strategic default-- where the borrower has plenty of income and a positive net worth, but simply chooses not to pay the mortgage.  While AMR may have enough cash to meet all their obligations for a short period of time, doing so would likely leave the company in a position where it would simply have to be shuttered, costing tens of thousands of people their jobs.  By declaring bankruptcy before that point is reached, the enterprise is likely salvageable, saving jobs. In the case of the positive net worth strategic defaulter, their decision is merely to benefit themselves at the expense of the lender.

One thing that I believe needs to be done is to legalize mortgage cramdowns in bankruptcy.  The fact that homeowners can't get relief from their mortgage debt in bankruptcy creates a mismatch between the set of people who truly need relief from their debts and those who can get it.

I don't necessarily think that legal cramdowns would cause everybody with an underwater mortgage to file for bankruptcy.  If cramdowns were legal, then I think banks would be far more likely to approve modifications and short sales for fear that the homeowner would declare bankruptcy and leave the fate of the mortgage in the hands of a bankruptcy judge.  So many underwater homeowners would not have to file for bankruptcy but they would still be helped by the possibility of a cramdown. 

Bankruptcy would be able to distinguish between strategic defaulters with a lot of wealth and strategic defaulters who have a negative net worth because of how much they are underwater.  I do not approve of strategic defaults, but I really do not consider it to be a strategic default in case when the borrower has just enough income to make their mortgage payment but is put into a negative net worth situation because of the underwater mortgage.  In these cases, the borrower is trapped in the home and the underwater mortgage will be a burden for years and years.  These are cases where the borrower should have the option of bankruptcy but currently doesn't. 

It's a wholly separate situation when the underwater borrower has plenty of income and wealth and they strategically default.  I think that is morally wrong and should not be encouraged.  One thing that could deter this kind of strategic defaulter is if banks had stronger recourse to collect deficiencies after foreclosure.  Perhaps there could be a tradeoff between cramdowns and recourse laws such that those whose mortgage was a legitimate burden could get relief in bankruptcy, but those with a lot of wealth would have no way out of the debt.