8 -> 16 GB RAM and 128 -> 512 GB SSD makes it $600 more expensive. A 512 GB NVMe SSD just doesn't cost $400 these days. Besides, why even use NVMe when a SATA SSD would be good enough for mac mini? I guess the only way to save money here is to get the 128 GB model and then use a SATA SSD with a USB adapter. $200 for extra 8 GB of RAM also sounds excessive although that's easier to swallow than the cost of the SSD. Finally, why is there no i5 (edit: quad-core i5) option? I think i7 is an ovekill for a mac mini, but i3 sounds like a very risky choice as it likely won't last more than a few years before becoming obsolete.
I think it's unfortunate that Apple decided to "premify" the mac mini.
Coffee Lake i3 is 4 core, 4 thread - in other words effectively the same as Kaby Lake i5. You could argue the toss over amount of L3 cache, the loss of turbo boost (vs a Kaby Lake i5), or the price, but any way you look at it the i3 is good value.
A Coffee Lake i3 at this stage should last years.
RAM is looking potentially user replaceable
Storage can be improved because of the versatile Thunderbolt 3 ports with a variety of solutions, even bus powered ones if you look at the Samsung T5 or X5.
i7 probably is overkill, especially if you run jobs on it that will make all threads fire up because of the increased power draw and therefore heat/noise. There are similar arguments running for the i7 in recent 27" iMacs but we won't know until benchmarks show if it throttles under sustained load. But one thing that you can't argue is whether or not it's a rip off as previous i7 upgrades in the iMac have been. Depending on the exact spec as paid to Apple, would the i7 upgrade be worth it? Your mileage may vary, especially after benchmarks.
