Furthermore LotR is a special kind of literature which can only be fully appreciated if the (sometimes complex) mythology is also thoroughly devoured.
: At any rate it ranks in my top ten list for certain.

IMHO that isn't supported by the history of publication. As we know the Hobbit and LOTR were published first. Due to the reader demand for more information, the mythos began to be released. Prior to that, what made LOTR so great? What continues to make it so great? More copies of The Hobbit and LOTR have been sold then HoME, Lost Tales or Sil. That should discount the belief that LOTR "can only be fully appreciated if the (sometimes complex) mythology is also thoroughly devoured".

-RR