I will tell you my logic when I followed my loan contract and avoid the moral decision
My past mortgage was 6% fixed and I could not get a refinance because it was underwater.
Today with my bad credit I will pay 10% or 11%. This is 4% over my old loan. This will cost me an extra $20,000 to $25,000 a year but it is tax deductible.
After a 40% tax benefit that cost me $12,000 to $15,000 after tax more per year. It would take 8 -10 years of a 4% higher interest rate to make up for the $120,000 negative equity
I feel I will be able to refinance in two years for another 6% mortgage.