I agree with you..
If the new Mac Pro doesn't have better CPU options than the iMac Pro, I'm going to be pretty disappointed. Granted, the top end iMac Pro covers all my computing needs. If Apple makes the new Mac Pro as much more powerful than the iMac Pro than the iMac Pro is from the iMac, that would be impressive!
It would be more spectacularly impressive. But the Mac Pro 2013 was spectacular. Apple (and the vast majority of users don't need a stunt or impressive) need a tool that has a sustainable business model. Period.
Too high power and the niche is so small it isn't sustainable. Many folks are sitting on these systems longer so the number of folks coming up for upgrades is shrinking. Increasing that shrink by jumping even higher is just as likely to put the product on a death spiral as anything else. ( less people so charge more so less people so charge more .... death spiral )
It isn't about bragging rights on CPU. The CPU on the Mac Pro and the iMac can be the same because they systems as a whole offer substantively different things. There are very few users who are just solely focus solely on CPUs.
Those who need their own screen(s), add-in cards, a GPU vendor different from the one Apple picked for the default GPU , etc. can buy the Mac Pro even though the same CPU could be in an iMac Pro.
If the CPU is the only factor and want to just pull the machine out of the box, plug it in and use it then the iMac Pro is better. If already have screen and replacing a tower/module box and that is it then the Mac Pro would be better. Different people have different needs even if have a single primary criteria there area
always secondary ones to do the product discrimination on.
There are more dimension to these systems that just CPU. The same is true for GPUs. Solely wrapping the systems around a specific GPU is myopic also.
The iMac Pro has other rather significant limitations.
1. It has a singular storage drive. Just one.
Folks who like to put 8-10TB of storage inside the computer the iMac is a non option.
Even with just 1-3 HDD SATA drives the Mac Pro would pull away from the iMac Pro.
Even if Apple stuck to their path of "SATA is dead long live PCI-e SSDs" 1-2 M.2 SSD empty slots would be a substantive improvement over the iMac Pro's limitation of just one proprietary SSD.
2. a Thunderbolt v3 eGPU PCI-e card enclosure can't solve some problems.
8K RAW video capture. Nope ( does most pros need it, no? but some do)
lowest possible latency audo capture. Nope. (does most pros need it, no? but some do )
.....
also if folks have a PCI-e card that hooks them to some > $10K system they get kind of twisted about sunk costs. If that is more than what they paying for the Mac Pro (or iMac Pro ) then have a tail wagging the dog effect. They want a slot in the system to put the card into to turn the whole thing back on. That's mostly it.
Just giving folks a single x16 slot to stick a card into would be a major separator from the iMac Pro.
3. some folks want to put the Mac into a rack because there is a set of equipment that provides the solution. (e.g. mobile video capture system that take to locations bolted to a rack with wheels. ). The iMac Pro llkely isn't going to work. If new Mac Pro was standard rack friendly it would be easy to bolt in. The CPU and GPUs differences between the to may not matter much in that context.
This whole mindset that the Mac Pro needs to be some tech spec porn dominator over every other possible Mac is alot of the junk that got to the Mac Pro 2013 designed into a corner. It doesn't.
Primarily it needs to solve a substantively different set of problems for a different set of users who are happy with the iMac Pro. That's it. Do that and the iMac Pro and Mac Pro can share components to offset the too low volume to be viable for Apple market constraints. Mac Pro doesn't need to beat up on the iMac Pro ... it just have to be different enough so there is limited fratricide sales between the products. Two fraternal twins that are different. Same parents but look different.
Dual Xeons is a dubious "look different" metric when there are so many others.