My impression, from reading his preface to Lord of the Rings, was that he disliked the interpretation to be too obvious, and forced on the reader. He expected readers to build their own interpretation.
“I cordially dislike allegory in all its manifestations, and always have done so since I grew old and wary enough to detect its presence. I much prefer history – true or feigned– with its varied applicability to the thought and experience of readers. I think that many confuse applicability with allegory, but the one resides in the freedom of the reader, and the other in the purposed domination of the author.” Quote by J.R.R. Tolkien: “I cordially dislike allegory in all its manifes...”
And it is straight from Jesus’ most powerful words: the meek shall inherit the earth.
It’s not just the obviousness of interpretation; it’s the singleness of it. Myth opens up possibilities, allegory closes them. Again, it’s the difference between a “sign”—which aims to have a single, unambiguous meaning—and a “symbol”, which is forever open-ended and multiplies meaning.
There’s a road sign where I live that says “Brisbane Street”. It is meant to be unambiguous, and boring, so that people can find it. And it succeeds.
But when Tolkein said, “the road goes ever on and on”, well, he was talking about different kind of road.
Still 'round the corner there may wait
A new road or secret gate;
And though I oft have passed them by,
A day will come at last when I
Shall take the hidden paths that run
West of the Moon, East of the Sun.
