Autopsy of Windows 10 File History

I upgraded our family PC from Windows 7 to Windows 10 yesterday. My first impression is generally positive: our trusty old machine feels faster, and the operating system has many small improvements.

However, today I had a closer look at the File History feature inherited from Windows 8 and had to ask myself: Was this feature created by a trainee? Were the design and code reviewed and tested?

1. Files are copied to an external drive without any compression. Well, my drive is still large enough.
2. If the computer has multiple users who have shared folders in their libraries, the contents of the shared folders are copied to everyone’s personal backup copy. Buy a big drive! You can of course fix this by excluding the shared folders in each user’s settings, except that...
3. In my initial experiments, the modified settings disappeared.
4. Last but not least, all users of the computer have access to each other’s backup files. This could have been fixed by setting the permissions of the FileHistory folder, as Paul Coddington pointed out in 2013.

Is the File History feature intended to be just a toy?