One tradeoff you get with ANY high-end workstation (and the Mac Pro was never going to be anything else) is that the base model has an absurd combination of specs... I suspect that the case, power supply and cooling system
alone add up to well over $2000 of the cost - before they put the motherboard in (a workstation-grade 1.4 KW power supply probably costs Apple $500, then they mark it up to $1000). That 8-slot, 12-DIMM motherboard is a $1000+ item - here's a gamer version of a similar board for $1800.
https://www.newegg.com/p/N82E16813119192...
That leaves Apple with not a huge amount of budget for the other components - they spent most of the entry price on infrastructure to support nearly unlimited upgrades of the other components.
HP does
exactly the same thing - a $3000 entry-level Z8 performs like a $500 computer - the rest of the budget goes to supporting its massive potential. At least the base model of this thing is a viable computer (with the possible exception of the 256 GB SSD) - it performs like a $2500 iMac with a $200 RAM upgrade, while entry-level Zs perform more like MacBook Airs.
HP will sell you a machine where
every component has to be upgraded before you get any use out of it. Apple's minimums are high enough that you might leave something at base if that particular component
doesn't matter to your workflow.
Yes, Apple chose a relatively entry-level CPU for the base model - to the relief of people whose work is exclusively GPU-bound. The CPU is plenty to run macOS and get the work to the GPUs...
Yes, that's a $200 GPU in the base model - to the relief of people whose work is
CPU-bound. It'll drive any display, and there are plenty of workloads where that's all that's needed.
32 GB of RAM is definitely low for this type of machine - but (unlike HP's default 8 GB), it's plenty to run the operating system and support an application that is doing the heavy lifting in the processor cache (small, very fast data set).
No, I don't know what the purpose of that 256 GB SSD is - maybe there's a case where the application is relatively small, and all the data lives on a NAS, SAN or in the cloud?
If you were going to leave
all the options at base, Apple has other machines for you for much less money (including a 4 lb one that runs on batteries - a top-end 15" MBP will outperform a purely stock Mac Pro). They'll also sell you an iMac or an upgraded Mini.
On the other hand, each
individual option could make sense at base for certain uses - a musician might be happy with the base GPU (although she chose a 24-core CPU and 192 GB of RAM), while an AI researcher whose code runs exclusively on the GPU might choose a Vega Pro Duo (or even two of them), but the 8-core CPU and 32 GB of RAM are fine for getting the code to the serious processing in the GPUs.
No, Apple didn't cater to people who wanted an expandable midrange Mac - something like a Dell XPS tower. It would be
possible to use the base model that way, but you'd pay literally thousands of dollars for cooling, power supply, chassis and slots that you don't need.
They have maintained for over 20 years that this market is better served by largely sealed computers - cue gnashing of gamer teeth.