Great explanation, very reasonable.

Except that before they did and then they didn't without any proper notification (release notes don't count for significant changes like this).

They should have just added a pop up or at least email or both, given a heads-up and then again when the change actually kicked in

Well, you missed the point.

The problem is not them not backing it up by default but:

* changing existing setting to backup less by default * essentially hiding the change from the user as it is not shown on directory exclude list