Income inequality has grown dramatically in the US over the past 4 decades. Is that a bad thing? Why/why not?

Income inequality has grown dramatically in the US over the past 4 decades.  Is that a bad thing? Why/why not? What percentage of the US work force has enjoyed improved standards of living over the past 4 decades?  Who has received the productivity and income gains generated by the US economy over that period of time?  Should public policy be changed to encourage greater or lesser income inequality?  What changes would you advocate?