Well of course it is for Google to decide. They're the ones running the service. ;)

But again, if you ever want to retrieve all 5M files, I hope you're willing to wait a few weeks-to-months, because that's what it's going to take...

Which is why it's a terrible idea not to tarball them first to something more manageable in terms of latency per file operation.

It was not for them to decide up until now. And yes of course users were willing to wait $duration for it until now. If you are suggesting a work around that is okay. It is not okay for google to tell their users to tarball "now" "because".