Income inequality is an indirect, at best, and irrelevant at worst, measurement.
One cares about the average health, wealth, and longevity of a population. That continues to skyrocket as much of the third world becomes modernized due to economic freedom, the one measurement directly proportional to such measurements.
This continues to improve in the west, too. Their health is stalling, but due to too much cheap food and a lack of needing to physically labor.
Both of these are historically novel "problems", where most places and all other time periods, dollars per calorie and dollars per nutrition were the limiting factor to average health and longevity.