OK, second take at this, apologies for the misunderstanding the first time - I stopped at SIM having seen the LTE bit -
I'll start with the RAM issue first. The reason given for soldering RAM was to make it more reliable and to reduce the space required to enable Macs to become thinner (from being lower profile, lower power, and not having to cater for fat fingered users trying to remove it). Remember many manufacturers have since followed that example and do the same with ultra thin laptops.
And this is the point, Macs would still be a thick and heavy as the old 2012 Ivy bridge non retina MacBook Pro if they'd stuck with SATA, DVD, and replaceable RAM. That's 4.5lb (2.06kg) vs 3.0lb (1.4kg) for the 2012 vs 2020 M1 13" MBP.
The Surface Pro doesn't seem to be as thin as a MacBook Pro so I'll assume part of this is due to a certain level of serviceability.
Don't get me wrong here, I like a bit of serviceability and have added RAM and HDD/SSD to Macs before when they were serviceable. The fact that the 27" iMacs are upgradable makes them a great budget option for users who want more RAM.
Apple's next point will be about data security and reliability. Remember that they use some of the fastest SSDs available, and if it were down to an average computer user with replaceable parts they'll buy the cheapest they can find and then complain that their Mac runs like crap when it's the fault of the hardware they bought.
Remember Apple are going down a road with Unified RAM that doubles down on replaceable RAM and I think the storage is on die too - this is for performance and power efficiency reasons. They select the correct components to fit their design.
I haven't used this kind of argument in a while but how many people buying a 2230 m.2 are going to buy SSDs of a top tier quality? Are they even available because a cursory look reveals they are quite rare at higher capacities and seem to be dying out. They'll just buy cheap crap if they can and probably botch the install job. And If you're advocating that Apple leave an empty space in the machine for users to add their own storage then that's a massive error because for a majority of users it means the space will be left blank. If you think they'll out a 256Gb unit in there for people like you to replace with a 1Tb unit - great. But how well will it perform? And will you even be able to get a replacement in 4 years?
I have seen links for a Samsung 970 PCIe 3.0 x4 EVO 1Tb in a 2280 form factor (which is a lot bigger than the postage stamp sized 2230) for 122 quid on Amazon today. But a casual search for a 2230 didn't turn up much.
Let's then not forget that you can accidentally buy a SATA SSD in an M2 form factor. Imagine the frustration as the fat fingered user buys the wrong item. Thankfully these appear to be dying out, and manufacturers in the budget sector appear to be happy to swap controllers and hardware on the same product name items (bit underhand there).
If I were building a PC today I might look for a PCIe SSD to go on the motherboard but I'd buy a high performance Samsung EVO or Pro with true PCIe 3.0 x4 performance. I'd also look into the possibility of waiting for PCIe 4.0 for even more performance. Remember the very best SSDs are 2280, with heatsinks, and boast SERIOUS figures for read and write.
I daresay a lot of average Joes will be looking for cheap storage on a postage stamp they can just plug into a computer as easily as plugging in a SD card. Well, if you'd only just have a look at the murky world of SD card reliability and performance you might then come back and see why Apple won't want users raging on them after botching their install of a no-mark brand and the industry has moved on from that connector technology.
Yes, it's convenient, cheaper, but we've yet to see the performance figures for Apple's Unified architecture to see if it outperforms it to any serious degree.
