The problem is that LaTeX has a learning curve. Historically, any software with a learning curve at all has been pushed aside as soon as alternatives are available. It's why GUIs took off in the late 80s (and earlier for Mac and Amiga users.) People didn't have to learn anything to use a computer. Most computer functions were immediately obvious or took very little figuring out, as opposed struggling to memorize and learn the conventions of CLI.
I think the problem is that most people would rather do a lot of work to avoid learning a little, than learn a little to save a lot of work later. Why else would someone rather spend hours doing menial typesetting (one of those tasks computers are darn good at) than learn a little bit of markup language?
What inspired this post? I spent an hour today trying not to sleep in that gorram required technical writing class as the professor laboriously demonstrated how to craft a table of contents by hand in Microsoft Word.
\tableofcontents It's that easy, people.