Love the overall answers:
Generally speaking when we talk of Pro users, we talk of people who require workstation hardware.
This is often the creative professionals - working with 3D modelling software, game development software, high-end animation software, Final Cut Pro (and other NLEs) etc.
Workstation Hardware is a jaded concept in so many cases. In Applespeak it refers to "Xeon CPUs with ECC memory". Several of those creative professionals you listed, and I'll include photographers, graphic (independent and agency types) and industrial designers, have been primarily using the 2014-2017 iMac. I've also noticed a lot of photographers and web developers are now migrating to laptops, and I have to believe graphic designers are doing the same.
Corporate in-house departments actually require their employees to take their computers/workstations home after work. I could see the same being true of creative agencies (ad and design). With the highspeed internet, it's now easy to work from home and link to directly to the company's servers.
Professional Apple user workstations have been less reliant on Apple's definition of "workstation hardware". In fact, the whole point of the iMac Pro was inspired by these creative professionals already using the i7 iMacs as their primary workstation. The big thing Apple missed on was; those users partly chose the iMac because it was less expensive than the Mac Pro. It had a better "price-to-performance" ratio.
On the Windows side, the professional photographers, videographers and designers who use the same software for their professional work as their Apple counterparts, also opt for the 6700k/7700k and now the 8700K. There has even been a migration - me included - who vacated Apple and moved to Windows because we know Intel offers more than 4 cores in the i7 series.
With the x299 series, non-xeon CPUs directly aimed at the 'pro market', There is a LOT to option to customize your workstation for your needs. For Apple, if you want more than 4-cores, you needed to pay $4,000 for 6-cores, and $5,000 for 8-cores back in 2013. Right now, the 2013 Mac Pro is $4,000. For the tower alone.
I built my 7820x Radeon, 32GB RAM, RX 580 Capture One Pro workstation for $1,950. I chose the Meshify C case, as it has fantastic airflow. ...This is exactly the non-xeon hardware I've wanted from Apple for such a LONG LONG time.
This is where Apple is missing the boat for so many users. Intel offers CPUs to create a wide array of workstations for professional users of all types. Apple simply doesn't want to cannibalize their high priced Xeon workstations for less expensive solutions.
The machine I'd love to see from Apple, and I've mentioned this numerous times on these forums, is an entirely user-upgradable triple or quad height Mac Mini with 6-core 8700K, up to 64GB of memory, dual NVMe SSD slots and an internal 2.5" drive bay. I could deal with the GPU being proprietary in this smaller form factor, as you can add a secondary GPU via thunderbolt 3.
However, they Apple could also do it this way: 4-core 7740x, 6-core 7800x, 8-core 7820x, 10-core 7900x. They could use the Radeon RX 560 for their base GPU, and include an upgrade option to the Radeon RX 580, Vega 56 and 64 GPUs. If you wanted to get a GTX 1080ti, you can add that via thunderbolt 3.
The 7800x with the Radeon RX 580, an SSD boot drive and 16GB RAM shouldn't cost the buyers anything more than $1,800, with an upgrade path to the 7820x being another $300 an top of the $1,800 -- so looking at $2,100. Tack on another $100 for the RX 580 upgrade, and it's $2,200. Considering Apple would get their parts at wholesale, that's still a decent margin. I'd easily pay a $200-$300 premium for this over what I have no - as I prefer the Mac OS.
Case wise, even if they went larger than a quad-height Mac Mini, like this size, but obviously a different design...
https://www.newegg.com/Product/Prod..._design_meshify_c_mini-_-11-352-086-_-Product
...which is smaller than my Meshify C mid-tower - you still have plenty of room for internal expansion.
That would be entirely raging for the Apple user community - with an incredible amount of flexibility across so many general and pro uses. I'd be back with Apple in a heartbeat. Apple could still offer the Xeon and ECC workstations for those users who need that kind of hardware. But most people simply don't need it, nor want it.
I have absolutely zero hope this will ever happen at Apple - they're too proud/stingy/greedy/stoopid to do it.