On the invaluable Locus magazine website, I saw a link to an article about the lack of diversity in most science fiction. Unfortunately the way the article was titled was confusing. It started "Why are most SF authors straight, white western men?" and continued with "Science fiction writers can't ignore the diversity that exists on planet Earth." Those are two separate questions, though they may be related.
     Perhaps David Barnett, the author of the post, didn't write the headline. He expresses himself better in the opening paragraph:

     Science fiction loves a good paradox. Here's one for you: how can a genre that dreams up alien cultures and mythic races in such minute detail seemingly ignore the ethnic, religious, gender and sexual diversity right here on the home planet, here in the real world?
     In other words, for a school of writing that swims so deeply in the unconventional, why is science fiction and fantasy so darned conventional?

     The answer to that question may well be because most SF authors are straight, white western men. Isaac Asimov was a perfect example. A straight white western male, he was most comfortable writing about others like him. He was initially shy and inexperienced about women, so he rarely even included prominent female characters. (There are exceptions, most notably his continuing character Dr. Susan Calvin, the robo-pyschologist.)
      I suppose straight white western males could attempt to write about other genders, sexual orientations, races and cultures, but I don't think the critics really want that. When one does, they are accused of colonialism, insensitivity or just misappropriating other cultures, as was the case with Paolo Bacigalupi's The Windup Girl. 
     Acclaimed by both the science fiction community and non-SF communities alike, and winning just about every award for which it was eligible, Bacigalupi was excoriated by some because he dared to set The Windup Girl in a future Thailand, dared to have Mayasian characters, dared to include a Japanese-made female android who was turned into a sex slave, and dared to have the first character to appear in the book be a Western white male. This apparently was offensive and unacceptable. That his extrapolated future Thailand was not exactly like the present day Thailand, that it was not a perfect society, that he did not get every detail of the geography or language perfectly correct was further proof of the author's cultural insensitivity.
     I've written about why I find this criticism wrong-headed before, but in brief: Bacigalupi paints a pretty flattering portrait of Thailand following a genetically modified crop plague that has contaminated much of the world's food. It has also fared better than most parts of the world in the face of global warming and fuel scarcity. There's also a flawed but sympathetic Malaysian character. The straight white western male character is essentially the bad guy, though even he has some good qualities. 
     If you feel that the Japanese sex android is sexist and cliche, you may be right, but since the Japanese allegedly still sell schoolgirls' used underpants in vending machines (see Snopes.com), I don't think the Japanese have the right to be offended or to claim that they would never make android sex slaves. Monsanto has more right to be offended by the suggestions made about GM crops. 
     Windup Girl was such a successful book with such a complex and interesting setting that it's surprising Bacigalupi hasn't followed it up with a sequel, direct or otherwise (before the novel, he did a couple of shorter stories set in the same world). I suspect part of the reason is that he feels gun-shy after all the criticism the first book engendered. I wouldn't be surprised if he never writes another book that doesn't feature straight, white western characters in a U.S. (or maybe European) setting. 
     No one is required to like the book of course, but if non-straight, non-white, non-western and/or non-male readers can't tolerate The Windup Girl, then they don't really want diversity from straight, white western male writers. What they want is more science fiction by writers who aren't straight, white, western or male. 
     That's fine. Go write them. I'd like that, too -- especially if they aren't multivolume fantasies set in an ersatz Tolkien ripoff world or endless urban fantasies about detectives, vampires, werewolves or other shape shifters, witches, zombies and the women who love them. But if you complain about a lack of diversity and then vilify someone who makes a noble attempt (even if not completely successful) to comply, you really just want to complain.