Why is Salinger so strangely particular about that which appears of no importance?

Generally speaking, a published book carries advertising words, recommending words, or praising words, in its cover and introduction part, but any book by Salinger is exceptional in that point. Apart from the name of the writer and the story itself, one can see nothing written about the writer and the book. This is done according to Salinger’s demand, but why is Salinger so strangely particular about that which appears of no importance?
I would be far from being arrogant enough to say that many people misunderstand Holden Caulfield, but I think that it is forgiven to tell people that they will know what Holden is really like if they read ’Franny’.
For example, Holden retorts in his heart to old Spencer, who says that life is a game.
"Game, my ass. Some game. If you get on the side where all the hot-shots are, then it’s a game, all right―I’ll admit that. But if you get on the other side, where there aren’t any hot-shots, then what a game about it? Nothing. No