As I said, it doesn't make sense "at full price". Retailers other than Apple sometimes have sales, and sometimes even buying secondhand isn't a bad choice.
Oh, sure, it would be best to get it on sale, if possible. I can't recall if we paid full price or not, but that isn't the point. My son needed one, so the only real option was to get the mini as it is, or get the newer/better 9.7" iPad. Technologically and in terms of value, I actually tried to talk him into the 9.7", but he still opted for the mini.
When it comes to stuff like this (form factor, actual usability, etc.) it isn't about 'what's under the hood' and price as much as it is about what works best
I disagree that RAM is the determining factor. Apple always drops support for chip generations, even if devices with a given chip have different amounts of RAM, and devices with same RAM but newer chips live on. For example, the iPhone 5 (A6 Chip) with 1 GB of RAM is not supported with iOS 12, but A7 devices with 1 GB of RAM are, such as the iPhone 5s and iPad Air.
When A8 devices like the Mini 4 are dropped, chances are that newer devices with the same RAM like the 6th gen iPad will still be supported. Apple won't stop supporting a device that came out in 2018 at the same time as one that came out in 2015.
Hmm, I haven't looked at it for the most recent iOS updates (and model exclusions), but RAM has been pretty much the determining factor in the past. Maybe the CPU/GPU are starting to play a more important role in the experience... but having owned older and newer devices, I think RAM would still be a bigger factor. Maybe they just *finally* have enough RAM that it isn't currently a factor.
re: Apple wouldn't - the problem is that they are increasingly selling old models to hit more budget-friendly price points, rather than a feature-stripped model. So, instead of buying less capability, you're rally buying a shorter lifespan with the savings... so you're maybe not really saving much money, if any. That kinda sucks, so I'm really against Apple on that one (hence why I complain when these machines aren't updated regularly).
Apple was still selling, if I remember correctly, one of the mini or iPad 2 models (as new) after an iOS had already been released that effectively excluded it. So, don't think Apple really cares so much about that kind of thing anymore.