Agreed with you up to here:
It's like complaining that a file created in unix has the creators username and time attached - where is the privacy!! It even logs atime and mtime!!!
It's nothing like that. The metadata you describe is stored in the inode - the file's low-level directory entry on the filesystem. It's not stored as part of the file, so if it is copied to another system - by email, f'rinstance - that metadata is lost. Well, at least that's true for classic Unix and ext.
That is a world away from metadata embedded in the file, in terms of privacy. And auditability.