That damages the user-friendliness of their offering, because users with that configuration are always one misplaced key away from losing everything with no way for Google to recover it for them (and yes, users will absolutely blame the company for this failure mode, and companies that do not offer this failure mode tend to succeed in the marketplace).
Systems providing such services exist; they aren't as popular.
https://tresorit.com/, for example, may be a useful litmus test to monitor for this use case. They've had to implement soft deletion because "The option to recover files has been among the top feature requests we’ve heard from our users and customers" (https://tresorit.com/blog/file-restore-launch/).
See my original statement; they're offering an easy-to-use system, and handing out foot-guns to users is the opposite of that goal. "Should" implies a forcing function that doesn't exist.
There are foot-gun manufacturers if people want an alternative.
