The LaHaye perspective, which is willing to discard the future, probably accounts for our poor performance in this genre. See this article, Futures for Sale.
His is a ‘ rapture’ kind of guy. That colors his writing ( as I would expect) But note that your sited source was written in 2006 and The End series continues to sell very well. Animal Farm, The Lord of the Flies, Catcher in the Rye there is fiction that does not have a happy ending by any stretch of the imagination. Farenheight 451 has a bit of hope as does War of the Worlds but face it a lot of fiction ( science and other wise) is just plain morose.