In answer to Topical Tom, I think there ARE still plenty of people writing protest songs: I base this view on what I hear from various songwriters I know. OK they may not be megastar world-famous singers, but subjects from bankers to food banks, military conflicts, fracking, profiteering, independence (or not!), Facebook - you name it, anything you can protest about, they do it!
Oh, and I wrote one about getting an erroneous parking ticket. (They eventually admitted it had been issued incorrectly!)
Protest songs are definitely not dead.