Income inequality, revisited

How can anyone be upset that income inequality is rising?

The US has a large number of people with almost no education on one side (and this may be rising due to immigration), and people doing the most advanced and productive technological and business processes on the other. The most well paid people will be using skills to be most productive, while the least well paid people will continue to do the least productive unskilled labor.

I should add that since minimum wages reduce the hours available to the poorest, they may also enhance inequality, especially through reductions in lifetime wages due to lack of work experience because of unemployment.