I think it's mostly to have a price tag that doesn't immediately turn off people.
Yes, Apple is expensive in general, however people are generally fine with paying a premium. But if they'd come at you immediately with the full price for a reasonably specced machine, it would still turn many people away.
Instead they fix you on with a high, but still somewhat reasonable price and then upsell you in steps for everything. Like sure you could buy the 128gb iPhone pro, but then the storage will fill up fast with photos and videos. A great camera system being the huge selling point of the device.
On a side note I actually find the 256gb non upgradeable/replaceable ssd much more egregious, than the 8gb RAM.
As you say, for people with basic needs (and that is actually a quite large group), it is enough for daily use. Those people just browse the Web, view photos and write short documents in word. However especially if they have an iPhone and take lots of picture/videos, they will still fill up that storage fast. And then it gets really frustrating, unless you maybe pay even more to outsource everything to the icloud and pay monthly.