I agree, though i really really wish they didn't, it works great for the consumer space but as you alluded to, for a workstation the inside matter most. If Apple weren't so "proud" they could have made an cMP V2, slightly slimmer (remove 5.25" and 3.5" bays, would make some people mad but hey), about the size of the Dell Precision 5820 is a nice size, single or dual socket, 3-4 16x PCI slots, if they had gone this route instead of the nMP, or reversed route after they realised its limitations they could have launched an updated Mac Pro at every single new CPU and GPU architecture launch. Now, when the modular Mac Pro launches, the nMP will be 5 years old, launching 1 year after Intels CPU and AMD GPU launch, thats crazy how Apple really let themselves go when it comes to their workstation platform.But I guess my point is - I don't see them building something that *isn't* special or revolutionary or at least unique in some way. That's just how they've always done things. However, as well all know, this is sort of a commodity space...it's mostly about what's inside.
On another note, does macOS still "only" support 64 CPU threads? The current enterprise CPU:s are close to the limit, even for a single socket Mac Pro, easily exceeding 64 CPU threads in dual socket platforms.
A shame Apple probably never will let go of hardware + software bundle, atleast they could create an enterprise license for hardware allowing running macOS, then we could build pretty sexy machines on our own that could be running macOS (when hackingtosh are not an option)

http://wccftech.com/asus-ws-c621e-sage-dual-xeon-workstation-motherboard/