Surely the Lord of the Rings is capable of standing on its own to someone who has not read any of the supplementary novels. Otherwise, you're accusing 90% of the readers of Tolkien of misreading him.
You could think of the Silmarillion as a world within which the Lord of the Rings can exist, and the Last Ringbearer as another one -- just as the real numbers can be constructed within multiple different set theories, and remain the same object.
Certainly LOTR is capable of standing on its own, same way that "Hamlet" is capable of standing on its own. But if you want to discuss Shakespeare seriously (the same way author discusses Tolkien as an author), then you better have read a few more of his works as well.
Instead of saying something to the point of "Shakespeare consistently only wrote tragedies about kings partaking in murderous plots" based just on your reading of Hamlet and Macbeth, while never having read "Midsummer Night's Dream" or "The Taming of the Shrew".
This may be old news to some people, especially the Russian speakers, but I didn't see an article about it here.
In 1999, Kirill Yeskov, a Russian paleontologist, wrote The Last Ringbearer, a 270-page take on Lord of the Rings from the point of view of a medic in Mordor's dying armies who is also a "skeptic and a rationalist." In fact, Mordor represents the forces of reason in this retelling of the story. As a Nazgúl (himself a former mathematician) explains, Mordor is "the little oasis of Reason in which your light-minded civilization had so comfortably nestled." Barad-dur is "that amazing city of alchemists and poets, mechanics and astronomers, philosophers and physicians, the heart of the only civilization in Middle-earth to bet on rational knowledge and bravely pitch its barely adolescent technology against ancient magic."
The story has been newly translated and is available in free PDF form -- in English and the original Russian. There's a recent review from Salon as well.