I still find that VERY strange. On Elevation and Vertigo tours they easily sold out 2 nights at the same arena, and on 360 in Denver they played to over 70,000. For I&E, They only sold 28,000 / 36,000 possible tickets. I guess in the aftermath of SOI their image took a major hit, they weren't the "must-see" show at that moment.
The fact that the shows this summer have sold so well tells me that no permanent damage was done to their reputation, but people were just a little put off in 2015.
Well, I would say using this the Joshua Tree Tour 2017 as a gauge as to whether demand is up or down for the band live is probably not very accurate. This years tour has a limited number of shows and is a unique nostalgia event that will bring out all types of fans. I'd expect you'll see demand levels return to what they were when the Innocence And Experience Tour continues. They'll be keeping that in arenas. Although this years tour is more in demand, notice they did not book a show in Denver.