Not allegory, for that directs or rather insists on taking the reader to one precise comparison, but metaphor, where the reader participates in the applicability.
Overall, the entry there appears quite good (to my eyes) for it's depth & range of discussion. There are numerous links embedded there, leading to more information, including critics;
The Inklings, reviews were mixed. Hugo Dyson complained loudly at its readings, and Christopher Tolkien records Dyson as "lying on the couch, and lolling and shouting and saying, 'Oh God, no more Elves.'"[4] However, another Inkling, C. S. Lewis, had very different feelings, writing, "here are beauties which pierce like swords or burn like cold iron."
With other later criticisms themselves being criticized;
Moorcock's essay has drawn criticism for its portrayal of the themes in The Lord of the Rings and Tolkien's other works. Epic Pooh accuses Tolkien of glorifying war, preaching "cowardly self-protection," avoiding the subject of death, and forcing a happy ending upon the reader.
The ending, for my own readings, seemed sad, amid the poignant note of the Elves needing retire to (an admittedly vague) "Gray Havens" where their once known immortality would slowly fade. But not all the once immortals (taking along Bilbo & Gandalf) sailed away [from first listed link]
Finally, in one of the appendices to The Return of the King, after more than two hundred years of life Aragorn dies in his deathbed, leaving behind a lonely and now-mortal Arwen, who travels to what is left of Lothlórien to herself die on a flat stone next to the river Nimrodel, having returned to one of the few places of true happiness she knew in her life.
There was a handful of famous "rock 'n roll" songs inspired by the Lord of the Rings, most famously from Led Zeppelin (in case some here didn't know that, ha!)
I did run across an interesting, suggestive explanation which somewhat assists interpreting the riddle, or leading the listener in a certain direction in understanding the metaphors concerning "the lady" in Stairway to Heaven, with myself being led to think of the love for what was good & right that the elven princess Arwen carried as "lady of the light" and what she gave up *[to bring the balance back]* in the preceding song on that album, yet gained still(?) shared love with Aragon
Eh, probably reading too much into all of that...
The suggestion for interpretation found on a webpage discussing the preceding related song, primarily The Battle of Evermore with that one needing to be taken in context to see all that lovey-dovey in Stairway, with better copy of the lyrics found *here*.
As to the aforementioned Stairway there is an incongruous re-phrasing there of Tolkien's beginning line of http://allpoetry.com/poem/8500017-Song_Of_Aragorn-by-J_R_R_Tolkien "All that is gold does not glitter", with the editor there noting the resemblance to lines from Shakespeare's Merchant of Venice. In the Stairway version, clearly influenced by Tolkien, the line is rather inverted in meaning, making the Lady to look the fool at the beginning, saying;
Being as Plant & Page were rumored to have been satanists during that period of their musical careers, I suppose it is fitting that things might get twisted in opposite directions, leaving one thinking love for fools, if reading into the Zeppelin song's metaphors, as suggested.
[can anyone follow all of that -- or is it all too much?]
For any who have read Lord of the Rings, but not heard one of the LedZep songs mentioned, once one "prays up" a bit, with mind towards protecting themselves from possible demonic influence carried along by the song, here's a
which I cannot vouch for soundwise -- no sound on this 'puter. But it's a interesting song, with the mandolin, and call-and-response style to the lyrics that rather evokes a Lord of the Rings sort of clash between forces both good & bad. It's rather disturbing to hear the narrator voice such seeming enthusiasm for the ring-wraiths, but still overall "evocative" as to mood, fitting loosely with the set-piece battles at Helm's Deep, and the final large confrontation near the end (of LoTR), but still leaving me wonder just who's side Zeppelin was on?
Returning to the literary LoTR itself, another short discussion of themes within http://www.novelguide.com/TheFellowshipoftheRing/metaphoranalysis.html
And I always thought that the song was about a junkie looking for her dealer so she could get her next fix:
There's a lady who's sure all that glitters is gold
And she's buying a stairway to heaven.
When she gets there she knows, if the stores are all closed
With a word she can get what she came for.
...Your head is humming and it won't go, in case you don't know,
The piper's calling you to join him,
Dear lady, can you hear the wind blow, and did you know
Your stairway lies on the whispering wind.