I agree. I recently purchased an iPad Mini 4 when the price dropped.
It ran iOS 11 out of the box and whilst it started off a bit laggy it seems to have smoothed itself out. Everything is smooth and very responsive. I don't want to upgrade to iOS 12 just yet.
If Apple released a Mini 5 with bezel reduced display, no home button, Face ID etc early next year then I will still be willing to get one.
My iPad Mini 2 is still running iOS 9.3.5.
I'm tempted to upgrade to iOS 12 because I love the gestures in iOS 11. But I'm not sure if iOS 12 is going to be slower than 9.3.5. .... I don't want to risk it. :\
A month ago I would have told you the best iOS for the Mini 2 was iOS 10.3.3 while iOS 11.x killed it. But iOS 12 brought it back to life.
I'm stuck with an original Mini running 9.3.5 because last spring I traded my Mini 4 to my son for his Mini 2 so he could use it for college. And then after iOS 12 came out, many developers stopped supporting iOS 9, and my mother-in-law couldn't run some of her favorite apps on her Mini. So I had to give her the Mini 2 with iOS 12.0 on it, and take her Mini 1. She was thrilled to have things running so well.
So, the Mini 2 with iOS 12 runs just fine, and certainly much better than the original Mini that I have with iOS 9.3.5, yet mom-in-law's original Mini with 9.3.5 is still noticeably quicker than my Kindle Fire 8 HD that I got earlier this year. Th
APPLE, I WILL BY A MINI 5 OR MINI PRO AS SOON AS YOU MAKE ONE AVAILABLE.
My Air 2 is slightly quicker than the Mini 4, but not by a lot - my main issue with the Air 2 is that it, like the other full size iPads, is too big to put in a jacket pocket or cargo pants side pocket.
Since Mini 4 is old tech and came out in 2014 with the iPhone 6, and we've had 4 NEW generations of phones and iPads released since then, I feel like a mini 5 should be out any day now and I'd be throwing my money away on a mini 4 that would depreciate by 50% immediately upon the announcement of a new one.
My iPhone Xs Max will never be an iPad replacement (more like an iPad Micro). The icons should rotate in landscape mode like the 8+, and not all of the 2-column apps work the same as the iPad (i.e. mail), and a split screen mode and PIP would not be good on such a small screen, so it's missing that too.
PS: while I wait for an iPad mini 5, I've taken to using a Kindle Papaerwhite 3G, since the Fire HD 8" and iPad Mini 1 are so slow.