It's actually useful.
My strategy with those was to make the .dotx read-only and remove delete permissions so it was also in-tact on a network drive, and office workers can double click to start a company form letter.
"Locked" files behave similar to "Stationery Pad" files, though with slight differences in workflow. You can open a "Locked" document, but when you attempt to make any changes to it, the program will pop a modal informing you that the document is "Locked", and asking whether you want to 1. unlock the document (and then apply your attempted change to the original); 2. duplicate the document (and then apply your attempted change to the duplicate); or 3. cancel your attempted change.
"Locked" documents entirely subsume/obsolete "Stationery Pad" documents, IMHO. Locking gives you all the benefits of edits triggering a duplication of the document; while also offering you the option to edit the original if you so desire (without needing to close out of the document and modify its attributes first); and without creating unnecessary duplicates when all you wanted to do was view the document.
The worse part is that it is indeed incredibly useful.
New File is populated from the registry.