I think Apple learned with the Air 1 and mini 2. Probably the biggest duds they ever produced, they couldn't even run iOS 7 smoothly. Now with iOS 9, the app switcher even runs at 20FPS. Lovely. On top of that, the app and page reloads. Unacceptable. These iPads would be incredible for a casual user who doesn't notice that kind of thing or simply don't care about it, but for the nit picky tech geeks like me, it is an absolute and total nightmare.
Can't wait to bail on this mini 2. Air 3 it will be for me. Hopefully that isn't a dud, because Apple seems to be following an "every other iPad" sort of cycle. Hopefully the A8X's power has reached the point where any successor can easily handle any new power-hungry change Apple throws at it. Like changing to an @3x display, more graphic intensive OS iterations... Etc.
I agree with you that the mini was underpowered with the A7. Thats because it's the same A7 that's in the iPhone 5s, whereas the iPad Air had a slightly over clocked version of the A7.