Don't confuse the man with the message.
There's enough room in this world for a few people to be selling vitamins or "information products" via infomercials, but that's only because there are a lot of people doing other things. Good for him that he found his niche, but it's totally misleading to suggest to everyone else that we can all race cars, dance competitively and live all over the world by following the exact same path.
Also, the suggestion that all favelas are just like "City of God" was pretty offensive.
At one point in the book, Ferriss himself (indirectly) provides the explanation for why his own book focuses so much on his particular experiences and goals: He prefers to read books written by people that have actual experience doing something, rather than theoretical extrapolations. And so he's written such a book. He offers you a recipe for doing what he did because that's what he knows how to do. What more can you ask from one book? If you want a book about how to live a happy life as a hacker or a priest, perhaps you need to buy a second book.
To me, the fact that Ferriss has a very different personality from mine is a big selling point. If I wanted a book on how to think like I already do, I could write it myself!
i also find that books written from author's experience superior
examples: pg's essays, htgr by felix dennis, ferris among others
actually pretty much everything else (author who sings own song, cook who eats own food, etc)
With regards to the social implications of 4HWK, As had been said in many of the comments here about it, the idea is to be able to do what you want to do, whether it is to indulge in what you consider as fantasies, or to throw yourself back into doing another time-consuming, socially-productive startup.
I think you underestimate the difficulty of having nothing to do. In those moments, there is nothing to distract you from taking a good, hard look at yourself. There are many things that come up, assumptions about what is socially acceptable (getting a job) and what is not gets examined. I've done a bit of that in the past before, and I recognize it in Ferris's words at the beginning of his book. If after going on this imposed exile for a year, you come out of it going after a new dream, or a new project, that is often more true to yourself than running around being "productive". It is the equivalent of reaching the self-acualization stage of Maslow's ladder, and being ready to go beyond that. This experience is life-changing enough that I think people should have the opportunity to give it a try. Yes, it requires the cooperation of other people helping you out. What of it?
The other side of it is that American society may value egalitarian hard-work, but much of the middle-class affluence is founded on those living in harsher working conditions. Basic things as simple as running water, toilet paper, nutritionally-balanced meals, junk food, iPhones and news.ycombinator.com are all taken for granted here. They are not universally available. It is one thing to criticize Ferris's method for resembling an unsustainable Ponzi scheme, it is quite another to describe it as indulging in fantasies and gloficiation of no-work when the average, mainstream American middle-class is affluent by world standards.
Personally I wouldn't just travel (maybe 2/3 months a year), I would write libraries to help the programming languages I like and do various CS research. I think there is so much more to discover in our field.