So there's no way of running it on earlier versions of iOS? That's a bummer. Understandable, but still a bummer for me at least. lol
As time passes, Apple makes it impossible to "compile" code for the older version of iOS. However the major contributing factor for iOS 9 this time around was Dropbox. They changed their API (Application Programming Interface) and the minimum iOS that it would run on was iOS 9. The killed support for their previous API and it would not run anymore, so we were force to make that the minimum version. We always try to support the oldest iOS versions as we possible can.