I'd love to see Mellencamp live. I had tickets 12-14years ago but gave them away because I had to work.
Seems like he walked off stage because he was being heckled by a group of assholes in front of the stage. If it truly was politics related then John has paid his dues and has the right to say what every he wants. He will still sell out concerts regardless but at this point in his life I don't think he cares.
Edit. I'm more discussed by a singer who smokes cigarettes. wtf?
30 years ago I went to see Steve Earle in a local theatre, great venue. 2 Minutes before Steve took the stage, a side door opened and 4 fat Hell's Angels bikers walked in with their dates and sat front row center stage. It was obvious that Steve was performing the concert for these bikers, looking, waving and pointing to them the whole show. The backdrop screen showed biker pictures, brotherhood bullshit. Something about a couple of bikers who had been put in jail for being bikers.
I'd never pay to see to him again. And I'm sure he doesn't give a shit.