Easy guesses: 1) Most income growth went to top brackets 2) More women in the workforce meant both less power to workers as worker supply went up, and also two incomes bidding on homes/products.

There has been a considerable amount of growth at the high end. But it's not being distributed down nearly as much as it once was. How many companies offer defined-benefit pension plans anymore, for instance? Nearly zero in the software industry; Garmin is the only one I know of that comes to mind. It's also well-known that executive compensation has skyrocketed while other wages have failed to keep up with inflation.

I don't think this is a complete explanation, though, and your point is a good one.

I also believe that the transition from one-income to dual-income households has had a pretty deleterious effect on the buying power of the average household. Rather than providing financial security, the second income led to a bidding war on homes, cars, and schools. It's a shocking fact that today's dual-income family has less disposable income after necessary bills than yesterday's single-income family.