[mhagain]

This kind of framing device is a common enough trope, at least in my own personal reading experience. Moorcock used it as well, for example the "Opium eater of Rowe Island" introduction to "Warlord of the Air". It's an interesting narrative conceit but I don't view it as significant.

We all know that Tolkien liked a good framing device, put significant work into them, and - in common with his main narratives - went back, revised, expanded, discarded or completely changed them.

So Lord of the Rings is feigned to be an editorial translation of the Red Book, and there is a great deal of framework and structure around that feigning, including translators notes, but absolutely none of it intrudes into the main narrative. The Silmarillion has it's own history here, where the framing device almost becomes as much a story as the tales embedded in it.

Tolkien admitted in Letter 160 that "I am not now at all sure that the tendency to treat the whole thing as a kind of vast game is really good – cert. not for me, who find that kind of thing only too fatally attractive" and that is really what we're seeing here.