Perhaps I'm just getting old, but it seems to me that unless one is in a production environment or in a scientific endeavor requiring extreme desktop computation, these new pro models are over-priced, over-kill trophies unaffordable to the vast Mac user base.
These models, especially when upgraded, are niche machines which will do nothing to reverse the trend of declining desktop sales. I would, however, like to see Apple make a commitment to Mac users that continues to improve their computing experience at a cost more closely commensurate with other available systems. That seems not too much to ask. The iMac Pro models, if not similarly overpriced, would have been the perfect basis for most power-users (Mac and PC) to take notice. The incremental speed and functionality improvements of the main Mac line have slowed. What has not slowed is the escalation in pricing.
Don't get me wrong... I have been a Mac user since 1987 and have enjoyed the evolutionary improvements of the Mac and its OS. I have also seen the diminution of financial importance of Mac vis a vis the iPhone for Apple. That will not be reversed. If Apple wishes to remain a significant computer manufacturer it must expand its base. To do so it must take a more realistic approach to its pricing.