Similar to Social Thinking, this narrative is all about the "WHY" of social interaction as opposed to the "how" or "what" (which are social skills.) This was created specifically for a student who had the social skills conceptually, and when motivated by an external reward or prompted, could interact with peers, but simply was not intrinsically motivated, and therefore social skills would not generalize. There are many kids on the ASD spectrum like this. For these kids, I believe there is no benefit in drilling or forcing these interactions when they see no purpose in it. This social narrative is designed to help them understand the 'why' of socializing, and help them see why they might want to practice and use these skills that they have.
Although I haven't yet, I could imagine at some point having a student who has mastered all of their social goals but is not generalizing and writing an IEP goal along the lines of "will identify/describe __# of reasons he/she might want to interact with peers." This book would support that goal.