People don't leave a bad review because they realise they don't need or aren't very interested in an app. It's because they need or want to use the app but are prevented from doing so by bugs or other issues.
>
> bugs or other issues
>
I have some experience running apps with 1M or more users.
In my experience, I see that 10% of bad reviews are due to bugs while 90% are because a user really needs the app/service, but it is not free.
Which also means this: if the application is useless (and just steals your data), then it will have good reviews.
Basically some free users when presented with “you need to upgrade to use this” will leave a bad review. And that is 100% logical: some users believe that all online software should be free. And they never pay for software at all (since their company or school pays, etc. - but they don’t).