Restoring backups should be given priority before adding new features. The “undo” feature is far from reliable and many, many times this has failed to work. In addition, the “duplicate” site does not work so that is not an option to save work.
Contacting support to restore a site that was working moments ago takes too long for should not be necessary. Time is precious for everyone and it is frustrating having to contact support when the “undo” feature does not work.
Perhaps it may take time to have full version history for the users. Still, user back up and restore are fundamental to a website builder. It is simply frustrating and the builder is becoming unusable for many because of the lost time not being able to restore backups.