I agree, I don't expect Apple to make 'my' dream computer, although they hit the sweet spot in 2015 with the MBP at the time i must say. Best overall computer in our household, even now. I like the Mac Mini (2018) as an update and a nod to the concept of a desktop box, but I think we are just arguing that this Mac Mini is just not 'good enough' as an offering for the cost vs. upgradeability. As for pitfalls of buying a Hackintosh, yes there are a few extra steps which will cost about 2-3 hours of extra work at a minimum: You need to assemble a shopping list from one of the online guides, then you need to enter the parts list onto an online retailer and maybe pay them an extra $50 or so to assemble and deliver it, and then you need to install an OS on it. The cost benefit will depend on how much your own hourly rate of work is, so for most people I think the Mini's price point makes this choice a real one. If money were no object, I definitely would be buying not just one, but three.
Unfortunately, the desktop PC of today is still a compromise machine, no matter how many cores they add to the base CPU, no matter which operating system it runs or who builds it. Cost is a factor, but expensive for one is almost always cheap for another. Just ask yourself which car you would buy, I can almost guarantee that for everyone of us that chooses a Mercedes or Lexus there are an equal number of people who see no value in buying more than a Hyundai or a Mitsubishi. Anyways, I am going off on a tangent.
To keep it economical, Intel is pretty much stuck at x16 lanes of PCIe 3.0 for the CPU. Most modern GPUs still cannot use all of those lanes (at least that is mantra that is repeated over and over), but telling a gamer that he can only have x8 lanes for his RTX 2080 Ti will not go over well. So, instead, all of those lanes go to one or two PCIe slots for one GPU or a 2-x8 SLI/Crossfire. This leaves us with 20 (H370) or 24 (Z390) PCIe lanes to use to our liking for high speed NVMe storage, GbE or 10GbE, SATA, USB 3.1, Thunderbolt 3 (if you can find it, and you sure cannot find more than 1 port), any other PCIe slots on the motherboard. More lanes than yesteryear, but none directly attached to the CPU and the piece de resistance - all of the extra stuff that makes a system go fast BESIDES the GPU gets shoved through and 8GT/s DMI 3.0 bus roughly equivalent to x4 lanes of PCIe 3.0. WAIT, WHAT!!! Thanks, Intel!
This wasn't a big deal even 5 years ago, when SSDs and high speed interconnects were either too expensive or just fanciful notions, but now they are here and they lead to a completely unbalanced system that favors the GPU and penalizes all other subsystems. Apple at least tries to build balanced systems and tests prove that Apple's systems are better all around performers (Linus Tech Tips). Yes, I can provide a link given enough time...
But the only way to truly ensure a truly balanced system is to build one using a CPU that contains a high number of PCIe lanes itself, which are not cheap, have never been cheap and will probably never be cheap. (Core X-series)
The only saving grace heading our way
might be PCIe 4.0, but rumors say it will be superseded by PCIe 5.0 fairly soon, before it ever gains traction. However, who knows when Intel will adopt PCIe 4.0 OR PCIe 5.0, as I haven't seen any news or even rumors.
I am typing this on a 2015 15" MacBook Pro 2.8GHz i7/16GB/1TB SSD/AMD M370X and it is a great machine, but it took 3 years and 5 iterations (some minor) to get it right. Along the way, we had GT650M issues that necessitated a Repair program from Apple, display lamination issues, lots of hate for removing the DVD drive, Ethernet port and Firewire 800 and saying Apple made it too thin and people still needed those ports (sound familiar), grumbling about soldered DRAM and the cost of flash storage plus the lack of industry standard replacement solutions (no m.2). I am sure I forgot a few other caveats. Boy, I remember the day of that announcement and the absolute hate and derision aimed at Apple that day. Along with them discontinuing the 17" MacBook Pro.
My point being, no computer is perfect, ever, a few come closer than others to you individually, almost none ever universally, and there are compromises all along the way that we have to endure and that engineers had to work through knowing they could not win. The Mac mini is perfect for me at this time and place. I prefer the soldered storage, because the onus is on Apple to get it right, not on me if I upgrade it to something that doesn't want to work and I lose data because I missed some esoteric issues with the controller. Yes, the prices could be lower and Apple could still profit.
Letting me add my own DRAM is a double edged sword. Apple's prices are too expensive (32GB is nuts), but now I have to make sure I pick the right DRAM and I have done exhaustive research only to still end up with bum DRAM where two sticks (16GB) was fine but 4 sticks together (32GB) was a recipe for kernel panics and random reboots (WTF?!?) The rest is like heaven. 4 TB3 ports, 10GbE optional, HDMI 2.0, two USB A, BT 5.0 and wireless AC, 64GB top capacity, 6c/12t Core i7.
The lack of a dGPU bothers me not one bit, although it would have been nice is Intel would have built special version of these CPUs with Iris Plus, one cannot have it all. All I want is one in my hot little mitts.