What I meant by "utterly meaningless filenames" was that the actual filenames saved on disk (when saved in the course filearea) are in fact the "contenthash" values, and those are somewhat unhelpful for any human being who needs to access those files, and what they actually are.
What would otherwise be the filenames that Moodle creates do seem to be perfectly logical and sensible, it just seems strange that the files don't get saved on disk as such(!) in the default location...
...although I see you note that saving to a designated directory could(?) give teachers access to the files saved there. For privacy reasons that would not be desirable. Are (non-site-administrator) users of Moodle actually able to determine the location of the saved backups via the Moodle web interface somehow and/or then access the backup files? (Shell access to the server is limited to only sysadmins, of course.)