Young novels as a life mean for adult world

Harry Potter, Artemis Fowl, Chronicles of Narnia... Robinson Crusoe, Zanna Bianca, El Principe de la Niebla (The Prince of Mist)... All these novels are in the "Young Novels" category and just for this fact too many times adult people don't read them.

I remember I read some years ago into an introduction of The Midnight Palace that although first books of its writer, Carlos Ruiz Zafón, were listed in it, adults could equally appreciate their magic atmosphere, their ability in carrying you in far fantastic worlds.
I've to admit I haven't ever read the most popular novels of Zafón but in my opinion he's right.
First the reason of the low success of Y.N. between adults is the prejudice.

In my honest opinion adult readers are owerweening: if they tried more times to read that kind of novel they would overtake theirself.