iPads are typically 4 year life at least.
Older ones cannot update to the latest iOS often times.
When Apps are updates for Apple's Latest and Greatest, it renders a lot of ipads unable to use the app.
For instance, we have 400+ machines with 9.3.5 iOS. Google updated Drive for 11.x iOS. It will not load on the 9.3.5 iOS machines. We now have to manually go to each one, open app store, and install Drive, which then offers the option of the older version of the app.
It would be very useful for us to have the option of previous versions for older iPads, either as a 2nd app, or that the JSS would sense whether the new app will work, or the older app could installed in its stead.