why do we automatically assume that a) it's sad that this is what Dean was into. He loves hunting, why is that a bad thing?? and b) that John wouldn't have noticed. John Winchester was bloody proud of his kids. Both of them. There's no reason to believe that John wouldn't have noticed Dean's pleasure and congratulated him on it (in a very manly, gruff sort of a way, sure). This does not have to be sad!