[Legolas]

In that thought, the author said so with no intention of changing his mind. Why would you question it? The issue lies within your difference with Tolkien, not Sharku. The book was published with his knowledge; also with his knowledge, he sent those letters out to readers who would undoubtedly share their findings with others who had read the book. The book is not a self-contained book. It has a own story that can stand on its own, but the nature of the book does not allow everything to be told inside it - that does not mean matters not contained were not already settled. It's part of a legendarium created by Tolkien. Not accepting something written in the History of Middle-earth would be more acceptable because many of those matters remain unsettled...the Letters are entirely different. Those quoted in my article linked to above are final decisions communicated to readers after the publishing of the book. Nowhere is there any doubt or incompleteness shown, or chance of Tolkien changing his mind on the matter. Your head is significant (and brilliant, no doubt, in some ways), but in such a matter, differing in opinion with Tolkien about what happens in his created world still matters little outside of it.

Still remains..."I see no point whatsoever, in any form of literary research, to question a 'fact' Tolkien gave us, within or without the fiction, since anything relating to the Legendarium is necessarily part of the fiction. What would be the point of denying the authority of a quote such as the one from the Letters, explaining that Sauron was of human form?"