Rising inequality isn’t a new concern. Oliver Stone’s movie “Wall Street,” with its portrayal of a rising plutocracy insisting that greed is good, was released in 1987. But politicians, intimidated by cries of “class warfare,” have shied away from making a major issue out of the ever-growing gap between the rich and the rest.

That may, however, be changing. We can argue about the significance of Bill de Blasio’s victory in the New York mayoral race or of Elizabeth Warren’s endorsement of Social Security expansion. And we have yet to see whether President Obama’s declaration that inequality is “the defining challenge of our age” will translate into policy changes. Still, the discussion has shifted enough to produce a backlash from pundits arguing that inequality isn’t that big a deal.

They’re wrong.

The best argument for putting inequality on the back burner is the depressed state of the economy. Isn’t it more important to restore economic growth than to worry about how the gains from growth are distributed?

Well, no. First of all, even if you look only at the direct impact of rising inequality on middle-class Americans, it is indeed a very big deal. Beyond that, inequality probably played an important role in creating our economic mess, and has played a crucial role in our failure to clean it up.