How far do we go to avoid taxes?

While discussing the automatic millionaire homeowner with a friend. I began to wonder if we as a society have become so concerned with avoiding taxes that we have forgotten what is most important to us. My friend maintains that keeping a balance on his mortgage is the best thing he could do because of the tax breaks. After reading the book I realized that if you decide to forgo the tax advantage on the house you can pay off a house about 8 years early! This of course depends on interest. The higher your interest rate is the more years you save. That made me curious about what people value. I personally would want the 8 years of freedom. What do you think? Eight years or a tax break?