I'm a long-time user of free/open source software, and write various things for both fun and profit. I don't take myself all that seriously and I do all of my own stunts.
You can find me at these fine establishments on the web: Open Source Musings, The Monday Kickoff, Weekly Musings. and The Plain Text Project.
Authored Comments
LaTeX is great if you're self publishing, submitting to a publication or publisher that supports LaTeX, or if you work for a company that uses LaTeX for documentation or internal documents. But for many writers, knowing LaTeX doesn't offer much advantage.
Many of us WISH they supported other formats
Watch who you say that to or around. There are people out there who will accuse you of stomping on open source if they hear you utter something like that :-)
Seriously, though, major non-technical publishers are very wedded to proprietary workflows that start with Word and end with something like InDesign or Quark or something else. For many writers, that's fine. They aren't techies, aren't interested in embracing their inner geeks, and are happy to continue with word processors. Unfortunately, that locks them into a proprietary pipeline which makes the whole process unsustainable in the long run.