Apple has a very narrow focus on video and music as their "high end market" and has had that for a very long time. They basically missed the boat on anything GPU heavy such as cutting edge 3D (rendering) and ML/AI. Good or bad choice? Apple seem to have found niche and seem to survive rather well without supporting these high end applications.
Part of the issue is the refusal to allow Nvidia into Macs. I suspect this is to keep CUDA out of macOS. If they allowed it on the platform, many cross-platform pro apps would default to using it, as it would be less effort than re-writing them for Metal. Then Nvidia permanently have a seat at the table and have leverage over Apple - if Apple ever released a pro machine without an Nvidia GPU, it would bomb.
The other part is that Apple likes slim laptops and AIOs, which preclude big honking GPUs. The Mac Pro is the only machine they sell that could possibly take them, and that's too small a market on its own. This is the problem with Apple's long-term refusal to make a machine equivalent to a typical desktop PC (i7 / i9 tower).
So if your machines can't have big GPUs, where does that leave you? Audio, video, graphic design and so on. Also, bear in mind that Apple's profitability mostly comes from the iPhone, iPad, services etc. The Mac platform pulls in less cash than AirPods, so whatever choices they make with it doesn't affect their survivability much.
The 2023 Mac Pro is boring and useful for some, but it seems like something they could have released with the M1 based Mac Studio. I think something did not pan out as expected.
It would seem so. But perhaps they just focussed on their mainstream models first, before getting to the Mac Pro. They only have so many resources, and the 2019 Pro was still relatively new. Perhaps they wanted to get the Studio established in its own right? Perhaps the M1 Ultra wasn't a sufficient step up from the 2019 MP, so they waited for the M2 (where it seems to have found its stride)? Perhaps 128GB was less than the typical load-out of a Mac Pro, but 192GB would be enough for most customers?
We'll find out in the long run if the Extreme is something Apple's interested in. Various people have pointed out that although it makes intuitive sense to the layman, it's not obvious how it could actually be made. The Max only has one UF connector, and to access any other die in single hop (to keep the latency low), it would need three. The edges of the Max are already filled with memory interfaces and so on.