When thinking about purchasing a house, if you are one of the very lucky few with access to enough cash to actually buy the house up front, here are a few reasons why you might consider still taking on a mortgage. The very largest reason, would be the tax deductions which you are eligible for when you have a mortgage on your house. If you own the house completely, then you will have to pay the full property tax every year.
Another reason is that it can be a lot easier to liquidate a house which you don't own fully.
Link: Should You Pay in Cash? (mortgage tips); Real Estate Ar