Given that it deafaults with 32GB, I really don’t think the non-upgradeable RAM is that big of a deal. There are some people that need more RAM then that but very few.
...yes, but they're highly correlated with the very few who actually need 8-core Xeon, ECC RAM and workstation-class GPUs for their 4k+ video editing, pro audio and scientific computing. I.e. the very people that the iMac pro is targeted at.
After 4-5 years, and if you update your software regularly, 32 GB might not seem like enough. Yet if I spent $5,000 or more on a computer, I'd want it to last longer than 5 years (i.e. spending $1000 a year on a machine is a lot).
OK, so here's the theory (don't shoot the messenger): the iMac Pro is aimed at serious callers only, who will be using it in a commercial/professional setting. Such customers don't buy a "jack of all trades" computer intending to upgrade it piecemeal over 5+ years: they spec a system for a well-defined purpose with the necessary specs and either get it on a 3 year lease or plan to replace it after 3-4 years once they've finished writing it off against tax. (Aside: Apple's panic leading to the strange Mac Pro press briefing last spring would have started about the time that the first cMP leases were expiring...) So the target customers of the iMac Pro really don't care about upgradeability.
Its hard to fault that theory without figures for how many potential customers
don't fit that profile. And that's the thing with all recent Apple launches: their design decisions are targeted at a particular "model customer" (preferably the one most likely to fork out a higher premium) and if you match that profile you'll love the product. (There's probably a Keynote slide for product design meetings that gives this imaginary person a name, biography, favourite emoji and shoe size). If you
don't fit that profile then you'll suddenly find that features that you know and love have been thrown under the bus - but Apple's profits are OK because although they've narrowed their customer base they've raised their margins.
...until the MacOS ecosystem starts to die because, unlike $5000 designer handbags (or maybe watches), $5000 computers need software developers, technical support, third party hardware, resellers, nerd evangelists etc. to succeed and your new narrow but deep-pocketed customer base isn't large enough or diverse enough to support them.
Over the long term, the new modular Mac Pro would be much more economical.
Go read the TechCrunch transcript of last spring's press briefing
carefully: what they said was very carefully worded and the only clue given as to what Apple mean by "modular" is that it doesn't have a built-in display. They describe their
current range as including "laptop, all-in one and modular" systems. There is no commitment whatsoever to offering
user upgradeable
anything - just Apple being able to offer a wider range of BTO options.
Now, maybe Apple
are planning a machine with upgradeable RAM, GPU, PCIe slots and internal storage, but that would be totally at odds with their actions over the past 5 years (including the design of the iMac Pro) and nothing that they have actually said is inconsistent with a souped-up, hermetically sealed headless box.
Plus, it doesn't take 18 months to build an Apple-sanctioned ATX Hackintosh in a nicer-than-average aluminium case, which is what pros, power-users and computing enthusiasts actually need (and, while deeply un-trendy, is still a readily available workhorse option in the Windows/Linux world). Nope, we may
want a pick-up truck but Apple are probably designing a sports SUV.