Apple offering expensive upgrades for storage and memory pre-dates the existence of iCloud storage by decades. It was entirely standard before MobileMe, or Apple offering any kind of "cloud" services.

Apple just charge a lot of money for upgrades, even did when it was trivial to do them yourself, and they're not going to change once they made it impossible to do any kind of internal upgrade.

You could upgrade pretty much all(?) Macs yourself back in those days, though