Whatever happened to Brother Rudyard?
Part of it, I think, is that the irony-challenged continue to read poems like The White Man's Burden as completely straight-faced odes to racism and imperialism, when the sense of irony present in his other works suggests that Kipling meant quite the opposite. Another part is that the early 20th century saw the ascendancy of what C.S. Lewis called the "men without chests," and we're still suffering the fallout from that today.
Kipling's biggest mistake, though, was that he celebrated what used to be called the manly virtues — strength, courage, honor, and patriotism — and it seems that except in tiny and unfashionable backwaters like science fiction, the literary world just didn't have much use for those things in the 20th century.
After all, as Lakshmi Chaudhry reminds us in this article, Hemingway actually wrote chick-lit.