These five cities are all really close to each other. It seems odd to saturate that little segment of the country. Is this Stonesland? More fans per capita in the midwestnortheast transition states?
Buffalo is the only New York gig, right? The closest to NYC and NJ. It's summer, people could travel from farther away. Philly is a big Stones town, fans could go to Pittsburgh. Detroit could draw Chicago fans. Columbus can draw Cincinnati, Louisville. The strange one is Indy because it draws from the Chicago/Cincinnati/Louisville area. And Indy has not been kind to the Stones attendance wise the last go around. (Voodoo Lounge). I think the idea of a July 4th concert with the possibility of a huge crowd, at a unique venue is what they're throwing the dice on. Plus, there's a huge demand, since they didn't stop there last tour.
The Indianapolis Motor Speedway was very aggressive in landing the Stones show, probably sharing the attendance risk with the promoter. You are right, Voodoo Lounge, 1994 was the last Stones concert in Indy. Hopefully the date and the venue lands a big crowd, although I know many boomers are turned off by the standing room only format and are not attending because of that.
If you're a real Midwestern Stones fan you can go drive a couple hours to Columbus from Indy, or Louisville, see 'em next Saturday, and then see 'em again in Indy on July 4th, with a nice break in between.