|I've seen some articles suggesting there's no "error" or "failure" here, and it's all by design, as Google has apparently been sending emails for months warning they'd be doing a massive cleanup of unused accounts. On December 1st, to be exact.
Coincidence? I wouldn't be surprised if the two events were related. Maybe they've started doing it on a small scale before pulling the trigger, and everybody's now finding out it's including stuff that should NOT be deleted (eg, data that is NOT inactive).
IMO: Cloud services claim to sell a solution for the lazy. The reality is that you shouldn't give up on the good old tried and true methods.
As per the subject line - make your own backups, because their EULAs sure don't say they're responsible for anything that happens to your data.