If you look at the history over say the last few hundred years, it seems that concern over inequality is correlated to overall concentrations of wealth. In addition to that, the way inequality is measured in the studies we get bombarded with always has serious flaws. Looking at countries with modern economies, would you rather be poor in the 17th century or poor today? Do you think the poor in the 17th century were obsessed with inequality?
Envy is a very important factor but should one be envious of the basic rights one gets compared to another? No it shouldn't be problem and we shouldn't have to fight for equal rights, but people have to. Inequality is not focused on wealth as much anymore but on being equal in power to the man next to you when stripped of money and status.