I'm not so sure that I'd agree with "seldom", and I certainly couldn't
agree with that the author isn't the best judge of "wonderful hidden
meanings" that he had not deliberated created.
J.R.R. Tolkien, in his introduction (or was it the preface?) to Lord of
the Rings attacked exactly the same point - he hated allegory as a
genre, and LOTR was consciously not an allegory, nor was it a
fictionalization of the Second World War, though he did acknowledge that
his expericences in the war could have colored his writing.
Keep in mind that Tolkien was an Oxford professor in philology.
Roy