The myth of the American Dream is the dominating factor in keeping people complacent in the United States. You know it -- work hard, and your life will improve. Well, maybe not your life, but your kids', or at least your grandkids'. If that doesn't work, it is the fault of immigrants, or the darn Chinese, or those welfare freeloaders.
The study of inequality has been going on forever. To give you an idea, the index used to measure how unequal the distribution of income is -- the "Gini Coefficient" -- was invented a century ago. So, why the sudden interest? Why worry now about something that has been the fodder of academics, politicians, and the media for so long?