There's no point where I go "Yep, mortgage is paid off, I don't plan on ever moving, or if I do, I can sell this house for enough to pay for another house that I can just move in to."
Any single month or year might be cheaper, but it still costs a lot more in the long run to perpetually be paying for your house.
Here's a link to a paper about it: http://www.nri.com/global/opinion/papers/2008/pdf/np2008137....
> Unlike people living in Western nations, residents of Japan have not benefited from an increase in the value of the nation’s housing stock. Houses here last only about 30 years on average, effectively making them a durable consumer good, whereas in Western countries a house is a capital good that will retain its value almost in perpetuity as long as it is properly maintained. The market value of Japanese houses falls even faster than they can be depreciated for tax purposes; after 15 years the typical house is worth nothing.
A big part of my net worth is the equity in my house. I'd be much poorer if my home depreciated to zero after 15 years.