These books also have in common that they cover topics that everyone has an opinion on, and that you can get really upset and angry over while not being in a position to really do anything about the "issues" they describe. As you say it's about how "something needs to change" but it's never the reader who has to change.

> Add some fears about the before-mentioned topics and there's your new book every few months, same content, different cover.

Talkshows and other media make these books even more profitable and popular. Publishing such a book almost guarantees that you'll be able to tour talkshows for a few weeks, give interviews to newspapers etc. as free marketing for your books.