I just want to throw my hat in the ring on this one.
My last two machines have been Mac Pros. A 2006 1,1 cheese grater followed by a Late 2013 (arrived in 2014) 6,1 trashcan. I was waiting for the next Mac Pro, however I had reason to need to upgrade quickly due to hardware problems and bought an iMac Pro last week. I'm very happy with it, by the way.
After saying my farewells on the Mac Pro sub forum I came over here to see what was going on with the iMac Pro and can completely agree with (mostly) everyone's comments so far. The computer is different enough to warrant its own thread. There, I've said it.
Apart from the screen, everything else about this machine is different. It's not a stopgap while we all wait for the new Mac Pro, as Apple have clearly indicated. They want to offer a range of machines that will suit different pro users. Some will use a MacBook, some might opt for the new Mac Mini. Some will continue to wait for next year's new MP. But for those of us who have bought an iMac Pro it most definitely 100% deserves its own space on the MR Forums.
EDIT: I've just started a new thread on the feedback page:
https://forums.macrumors.com/threads/new-sub-forum-for-the-imac-pro.2156227/