The 5k iMac and Mac Pro have easily user-accessible RAM that can be upgraded, by anybody who can follow instructions. The (intel) Mini and iMac Pro can have the RAM upgraded by any competent technician or more enthusiastic users.
Whether Apple sell "upgrades" or not is irrelevant - those models use bog-standard plug-in RAM modules (but yes, I think there was an "official" upgrade program for the iMac Pro).
That option is most likely going away with the new machines, and Apple kinda have an excuse for that if they can get better performance by using tightly-coupled LPDDR RAM (which isn't available in plug-in modules and relies on ultra-short traces connecting it to the CPU). However, it does make the range/pricing of RAM options an interesting issue...
(a) a manufacturer sold a truck with a feeble engine and limited cargo capacity people would say "that's a lousy truck - if I only needed to carry a week's shopping and not drive up any hills I'd buy a cheap compact, not a truck" and call shenanigans on them for using dirty tricks to offer a too-good-to-be-true headline price... and if they weren't careful, people who didn't do the research would buy the lame model then bad-mouth the company.
(b) I know this revelation could break the internet but computers aren't cars.
(c) This isn't just about "mid-life upgrades" - if you bought a 5k iMac from Apple with more than 8GB of RAM, then, sorry, Apple shafted you - whether it was your fault for not doing the research, or you had no choice because you were buying for work and had to follow silly rules (in which case, hopefully, work was paying) - Apple want $200 to add 8GB of RAM, Crucial want $177 for 32GB - just open the hatch at the back and plug-it-in. No brainer, really. I seriously doubt many people buy the higher-end 5k iMacs with 8GB and leave it like that. Since that option is probably going away with Apple Silicon, keeping the same RAM pricing strategy would effectively be a significant hidden price hike.
The question is whether 8/256 would provide an "adequate user experience" on a machine aimed at 5k iMac customers. I don't think it would - all these machines are aimed at heavier users already, and 16/512 is hardly pushing the boat out.
Plus, the M1 is really, really powerful, so the 24" iMac and M1 Mini are likely to mop up some of the lower-end 5k sales, and probably one of the main selling points of the M1x/M2/whatever will be larger RAM options (and more CPU/GPU cores, which need more RAM to feed them - remember, the Intel 5ks have 4GB of VRAM while the M1x/M2 will be relying on Unified RAM for everything).
Yes, traditional, replaceable RAM modules allow a user to save a few bucks out of pocket on RAM modules vs. purchasing pre-configured from the manufacturer. It's a game as old as MS-DOS.
Every manufacturer charges more for pre-installed RAM than one could pay for the bare module afterwards.
But when I was in corporate IT, that strategy was against company policy. The "savings" on the component part ignores the labor costs. When purchasing new machines we were required to specify a configuration that would be sufficient for the expected life of the machine. That became part of the capital cost of the equipment. Buying the parts later on (and having IT staff install them) would have shifted the parts and labor costs to the operating budget, which was frowned upon. And upgrading a HD? Forget about it - if you were going to take the time to backup the contents of the HD and restore it to a new HD, they preferred we invest that time on moving it to a new machine with up-to-date CPU and other subsystems.
Of course, do-it-yourselfers typically ignore labor costs, and there's no real difference between Capital Budget and Operating Budget. It's "sweat equity," or the pleasures of a hobby. They may boast, "I got X more years of life out of the machine for spending just $100 on more RAM" (or replacing the spinner with an SSD). However, if they lacked the skills or personal confidence to do the job, a repair shop might charge a minimum of $50 labor for a RAM upgrade and $200 or more in labor for the SSD. For that kind of user, paying the "tax" on factory-preconfigured gear is close to break-even, and may save them inconvenience and downtime.
As to the manufacturer who sold a truck with a "feeble" engine or limited cargo capacity... That's not what I'm talking about. It's up to the customer to purchase the truck they need, for the intended workload. One user's "feeble" and "limited capacity" may be perfect for another - some vehicles are optimal for cities where parking is difficult and speeds rarely exceed 35 MPH/55 KPH but become inefficient in suburban/rural use. You don't need a 55-foot trailer to deliver small packages to 30 addresses in the course of a day. That 55-foot trailer excels at pallet-load deliveries to warehouses and big-box retail stores.
Computers aren't cars, but cars and computers are both products. Nearly every product sold is purpose-built (not modular), and while marketing practices vary somewhat from product category to product category, company to company, the overall "rules" of commerce and marketing are nearly universal. Cars are frequently used as an example because cars are expensive, durable goods that fall within the experience of nearly everyone, and that also have supported extensive DIY maintenance/repair/upgrade activity over the decades and are also famous for the sales/marketing practices of their manufacturers and dealers.
I'm a "handy" person who grew up in a family with a long tradition of DIY repairs and home improvements. Arguably, I'm the most skilled of four generations of my family in that regard. House wiring, carpentry, plumbing, drywall, interior and exterior painting, landscaping/gardening, masonry, appliance repair, electronics, automotive, computers (of course), smartphones... I've done it all to one degree or another, sometimes professionally. Some of it I still do, but for many of these things I now prefer to hire a professional (sometimes even when it's something for which I can be considered a professional). Why? My time is precious, and for many tasks I'm also purchasing the fluency/experience of someone who does a particular task frequently. It would take me more time, I'm not the young buck I was 40 years ago, and there's the likelihood that I would do the job with less finesse/competence. The pro may also have tools that contribute to a job-better-done that would be too expensive for me to justify purchasing for a one-off job.
But back to Apple's configurations. Yes, I'm expecting that the big iMacs will not have the same RAM upgrade scheme we're used to - that's the price of SOC-style performance. So I'll have to do what I've done for many decades now - determine whether I'll need more than the X RAM and Y storage space offered in the entry-level configuration. I don't worry about the "Apple Tax" any more than I worry about the "Ford Tax" - if I need something more than a 4-cylinder 2-liter engine and space for more than two suitcases, I'll buy the model that suits my needs.
