Companies do not act according to their morals: they act according to their incentives. And there is an incentive to sell more iCloud storage if SSDs are hard to swap.
Except that when you don't have the disk space on your SSD to download the stuff from iCloud, the whole thing doesn't work. I think you've a conspiracy theory here.
When you don't, the local files that haven't been accessed in some time are deleted and only a local alias is kept. Next time you need it, it'll be downloaded.
