I'm quite the iPad mini fan. I even use mine as my phone too (VOIP app + buds) so it is as important to me as "the precious" is to most Apple people. There's quite a lot of consumer value in using it to be BOTH devices vs. owning 2 separate devices (not really that far apart in screen size)... even with a small selection of tangible tradeoffs not related to screen size... like pocket-ability.
But I'm not upgrading to 7 from 6. Why? While I can appreciate the spec bumps, the 6 is "good enough" for my purposes. And I see the loss of that sim tray as a sizable negative for travelers (as Esim seems to only really be adopted by the pricier players while the dirt-cheap data/plans require a SIM card). When I visit another country and need data for a short time, I'd like to spend only a few bucks for it (as is commonly available with sim-based players) vs. paying much more to as little as ONE available choice offering Esim (and in some countries, there are NONE with Esim). I covet consumer value and that choice undermines that value through my lens to save what should be probably near nill in cost for getting rid of the slot hardware. And let's not even attempt the "waterproofing" defense (plenty of tech with a slot are just fine in that way) or how Apple needs the space: this is no iPhone cramped quarters... there's plenty of room in an iPad case.
However, the biggest driver is that the 2 was "good enough" for my uses until the 6... so I expect the 6 to be "good enough" until about the 9 or 10. I look forward to iPad Mini 9 or 10 in about 2029-2030.
A curious difference between iPad mini and "the precious" is the so-called "long in tooth" effect is not so prominent. In other words, an iPad seems to continue to be nice and fast throughout the life of the latest and prior generation... unlike "the precious" which seems "long in tooth" curiously fast. I wonder why? (rhetorical). So 6 should still be quite good until at least 8 or 9 and maybe all the way to 10. I look forward to the bigger tech hop forward to those generations.
Other than the sim tray deprecation, I see nothing else negative about the 7. If I had Mini 3 or 4, I'd probably hop on 7 and look forward to approximately 11 or 12 as my next one. IMO though: I see towards ZERO reasons to jump on every generation of this product unless the one you own is dead/broken/stolen/missing and you need a new one now.