It helps that the book dodges the dry tone of some academic texts. Instead, it is clear and readable to those who are neither black belts nor who strictly know who Wittgenstein was. This is in fact the book's great strength. The layman really can pick it up, learn something new and enjoy it into the bargain.
True, some of the authors have arguments that will make you curse. In the end, fighting is fighting, and you do have to wonder whether punching people in the face can make you a better person, for all what some of the chapters say.
Yet that's the point. You're not meant to agree with all the book says. You're meant to come up with your own arguments, find out things for yourself and, of course, disagree when you want to.
What the book proves is that good philosophy and martial arts do in fact have a lot in common. Both embody a sort of structured conflict, and both - at their best - put great stead in testing your beliefs and not taking nonsense at face value.