Because of Google's abysmal customer service which is awful to the point that even googlers can't get help if something goes wrong?
The point of a cloud storage is that you want your most important files to be backed up somewhere that you trust. I don't trust to store my data with an advertising company.
$120/year for privacy and customer support may be worth it to you but for the vast majority of people it's cost prohibitive.
* Insync adds xml suffix to files with xml contents.
* Expandrive borks file editing sometimes (happened twice - it was enough to move to Dropbox)
I still use Google Consumer Storage though, thanks to Google Photos. Can’t get rid of it, nothing better feature, simplicity and maintenance wise.
That doesn't help if your target customers believe they can get the exact same thing at a much lower price. (And many of them get those services from their employers for free.)
The only way one would prefer something half-baked just because it's "free" is if they don't really care about robustness and dependability.
That said, maybe the current Covid crisis is hurting them more than others. I used to travel a lot and leave machines in different places instead of carrying a laptop everywhere. Now that I don't travel, "magic sync" is much less useful.