Earlier quoted context omitted.
I second this. Also you seem to have more erotic/unusual titles...
I think that's because vanity publishing is typically very popular amongst programming and "romance" authors.
The Leanpub workflow is totally free to use, and we're making it better all the time.
Now, frankly, I'm a programming book author myself (I've written 3 programming books) and we have tons of programming books on Leanpub -- but I really wish we had a lot more romance and other "genre" books than we currently do. I even went to Brisbane to speak at GenreCon Australia (http://www.genrecon.com.au/) in 2013 to try to jump-start this, but frankly our usability wasn't there yet. We'll get there.