This is the part which I would like to question.
Yes, it can be profitable for Apple when you pay their premium for extra ram and storage. Thing is, it probably also takes time for them to produce a unit with the desired configurations (a custom spec can easily push the delivery date out several weeks). The premium is there to cover the fact that these are likely very low-volume orders that come in sporadically, and it costs Apple money when they have to stop the production line just to fabricate a few custom models that ask for additional ram and / or storage (ie: no economies of scale).
Meanwhile, Apple stores and retailers typically stock the default model. I would really like to see how many people are ordering custom configurations and whether this is really that much more profitable over everyone else simply opting for the stock models.
It costs £200 to upgrade a MacBook Air from 8GB base to 16GB, while it costs £56 to do the same for a Lenovo Thinkpad T14 Gen 3 AMD.
Similarly it costs an additional £200 to upgrade storage to 512GB or £400 to 1TB from the base 256GB, while Lenovo charges £40 and £120 respectively.
Dell charges £100 more to go from 8 to 16 GB on the XPS 13, which comes with 512GB storage and can be downgraded to 256GB to save around £50.
Granted the storage is designed to be replaceable on the Lenovo, but the RAM is soldered on in either machine.
Accepting your argument that it will cost Apple extra to produce a non-base model, the pricing seems completely over the top compared to the competition. Even then, why would it cost double to go to 1TB instead of 512? These costs just don't scale.
The only logical explanation is that Apple wants to be compensated handsomely for what a pretty basic storage options in 2023.
The only reason I can think of for Apple to stock so much of the base model is because their data does indeed indicate that 8 gb ram / 256 gb storage is sufficient for the majority of their user base. Otherwise, it wouldn't make sense to devote so much of your production capacity to making something that nobody wants.
I'm pretty sure the base models work fine for a lot of users, although I'd wager that external storage (and cloud solutions) is now more common among users who'd previously stored everything internally. I'd be surprised if that was driven by consumers really preferring to constantly plug a hard drive into their computer as much as by users doing the math.
That's not only an Apple thing, of course, since most computers now come with 256 in the base configuration and a lot of users probably buy what's on the shelf and then make do.
The fun thing is that Apple explicitly tells you for some products, iPads for example, that you should consider going for more storage to future-proof the device, so even Apple doesn't really think that it's base options are really enough.
You are right in that most people do value thin and light laptops, and I am also willing to wager that they do not really care about the inability to upgrade it after the purchase. You are looking at someone like a student or teacher whose computing needs are not likely to change very much over time. They will use it into the ground, and then buy whatever the next best replacement is.
Why not just make 16gb ram / 512 gb storage the default then? Because it would be overkill for over 90% of MBA users, it just increases costs for Apple, and as a business, you don't give your consumers everything they want (especially when a lot of it essentially boils down to "I want more stuff for free").
In this context, I feel the more tech-savvy users here are making the mistake of valuing utility over aesthetics (a very common oversight made by tech pundits in the early days of covering Apple).
Partially agreed, although I'd also wager that the "tech-savvy" users often tend to treat the majority of tech users as complete illiterates who will throw their expensive machine in the bin because they couldn't possibly comprehend the complexities of putting in a new hard drive or more storage.
I completely agree that most users probably not consider whether they will be able to upgrade their machine a few years down the line at the time of purchase and that other factors, such as aesthetics, matter more.
I'm not willing to believe that the idea of putting in more storage when they run out of it is not an idea that would cross a teacher's or student's mind. The reason no one really does it anymore is because it's become incredibly difficult to near impossible and that's probably by design. Apple and others obviously prefer you to buy a new machine rather than putting in more or faster storage, more RAM, exchange your battery without taking it to their service point for a fee etc etc etc
I'd wager that especially now, when money is tight with rising cost of living and everything else that's going on, more people would extend the life of their machines if that was easy to do.