@turbineseaplane: As a mini 4 owner, I felt similarly when the mini 5 came out. A faster CPU and pencil input, but only the awkward pencil 1. Rumors of what has now become the mini 6 were already around, so I was a bit underwhelmed and decided to stay with the mini 4 for the time being.
Now with the mini 6 it’s a bit more clear-cut for me, and the CPU/RAM situation has become more pressing on the mini 4 (despite not having upgraded beyond iOS 12). If I owned a mini 5, I likely would be more hesitant now as well.
I’m glad they didn’t increase the outer dimensions on the mini 6, but I don’t know how I feel about the aspect ratio change, I’ll have to try it. USB C is a bummer, now I’ll need to pack two cables when traveling, or buy an adapter. I’d also prefer to not have the camera bump.
OLED would have been nice (though unexpected at this time), I’d be willing to pay a premium for that. Otherwise I’m not a fan of the new pricing at unchanged RAM tiers, in particular since I’d like more than 64 GB and the cellular version for the occasional travel use. That’s very expensive.
My other gripe are the color choices. I’m waiting for the hands-on reviews to make up my mind on that topic.
In the end the mini 6 brings quite a number of changes, most of which you enumerated in the first post, so it depends on how one feels about the individual changes, and how much one considers them an upgrade (or downgrade).
The one thing I’m happy about is that Apple is strengthening the iPad mini form factor, as opposed to dropping it as they presumably do with the iPhone mini.