The problem with the various workarounds (aside from way too many steps) is the assumption that an album is involved. Most of my tracks do not have albums, and are named and located with a complex expression based on tags, so difficult to do the same to a new, untagged file. My bad, except it's the right arrangement for my large library.
Also, some techniques assume a different file type (flac replacing mp3, for instance) but sometimes the replacement is of the same type, improved in other ways (I routinely edit live recordings to remove everything but the music, for instance).
What is needed is the very simple ability to right-click on the filename field of a database record (track), get a file open dialog, and select a new file to assign to the database record. Roughly the same as can be done with cover art.
Two ideal options:
A file selection dialog check box to auto-update the file from the database so it gets tagged immediately and fully (or, if not a tag-embeddable format, this creates a sidebar file).
A check box to rename/move the new file per the current Rename settings.
If this process could be done on arbitrary selected records (batches) it would be a fantastic, fast, simple way to update/improve libraries.
AND -- this method ASSURES that no data is lost, regardless of what tags can be embedded/sidebarred, because it preserves the exact original database record regardless of what media file type might be attached to it.
I think this is an essential MC path to take -- treat the database as primary, not the media files. In fact, MC is already on this path -- the database knows about cover art but the cover art doesn't know about the database, sidebar files are used when embedded is not possible, the database can have a record that points to a file on removable media, etc. Just make it "official" and then fill in the various operational gaps (such as, allow a database record even if there is no associated media file... long requested).