The same list you gave already applies to data already readable on Google Drive - most people have data that can be used against them on those drives. Also, many apps ask for (And get) permission to read contacts and messages on your phone.
Claiming that this is the reason is sort of like rearranging the chairs on the deck of the titanic when you can see the iceberg.
Much more likely it is to stop import/export to a competing app. The fact they will let you keep a local encrypted copy, but not an unencrypted one under any circumstances, is telling.
The number of people who use whatsapp is an order of magnitude or more than the number of people who consciously use Google drive, as in people who know google drive exists. Even the people who have google drive, most of them have much less intimate data on it than in their private messages on WhatsApp.
If we are to take the position that all users are tech literate and should be fully in charge of how their data is used, then even Cambridge analytica wasn't bad. People explicitly gave it access to data that was accessible to them. However, the uproar proves otherwise. People don't like it when they click yes yes and some random app has access to their social media data or messages. This is why Gmail also started requiring independent audit for all gmail apps.
And you are still avoiding the equivalence that everything you describe is already happening with sms messages at least, and generally much more. None of your arguments carry any weight especially since they don’t explain why it’s ok for data to be unencrypted on your google drive in the first place.
That wasn't the only argument though. If the data was encrypted with a facebook held private key, the user would still not be able to see it. If it was E2E encrypted with the only key being on the device, people will get mad when they reset their phone and get a new one, only to find their messages are gone.
SMS had the same problems forever, but isn't owned by a company, thus you can't blame xyz company if random apps access your SMS. No company got ever investigated by multiple nation states over that.
You still haven't addressed my main question though, how will a random app scraping your WhatsApp be any less of a scandal than Cambridge Analytica?
The same way random apps scraping your sms, a common occurrence, aren’t. The sms app is by google. The WhatsApp app is by Facebook. What’s the difference?
Claiming that this is the reason is sort of like rearranging the chairs on the deck of the titanic when you can see the iceberg.
Much more likely it is to stop import/export to a competing app. The fact they will let you keep a local encrypted copy, but not an unencrypted one under any circumstances, is telling.