Not only are humans usually against changes to themselves/their lifestyle/etc, but they can easily turn aggressive when a change is insisted upon. Sort of why Greece has been in such bad shape these past weeks.
Also, I'm not a fan of books myself, mostly because I can't keep my attention active enough to actually get something out of a book. You just need to... use a language in all its "glory" if you want to learn it (and implicitly use it) properly. That's why international English tests, such as the Cambridge exams, IELTS, TOEFL, to name a few, are divided into categories, generally: reading, writing, listening and speaking.