An article on The Economist website makes an interesting argument:
That the widening income gap between rich and poor should not necessarily be viewed as a bad thing.

Productivity and globalisation have caused real income to rise much faster for those at the top of the income distribution than it has for the poor and middle class. High earners experienced more than a 30% increase in their real income over the last thirty years. Meanwhile, the bottom 50% of wage earners saw their real income increased by only 5-10%. Though the disparity is striking, it doesn’t necessarily cry out for justice. Things did get better for workers in that bottom 50%; they just did so more slowly.

The article also points out that the income gap may have positive effects, in that greater income disparities create bigger incentives to get an education.

I’m dubious.