Appreciation of reading, as well as education, isn't decreasing because parents aren't instilling an appreciation of it. If one looked at the facts, one can see that young children do fine academically, but several studies, as well as research presented in Freakonomics, show that adolescent children are more influenced by their peers, and turn away from education as they enter junior high school. Cutting through the self-important belief that parents, teachers, and schools matter, one sees that fourth graders are responsive to parental influences, but adolescents are primarily affected by their peers.
What's to blame? I can offer several possibilities, one being the effects a grossly unequal society; high economic inequality correlates with low measures on tests comparing academic abilities between countries. Why this is so is subtle, but it could relate to a culture which primarily appreciates education as a path to make money. Other causes, include, a culture devoid of quality of life concerns, and one that values working, but not leisure. Additionally, the push to regiment education in young children drives children away from education as they enter adolescence, such that increases in 4th grade academic performance are matched with decreases in eighth grade academic performance; American 12th grade performance, as compared internationally, is a joke. And then there's explosion of media culture.
Like much of the focus on education in general, the root causes, hence, the provided solutions, are incorrect and inappropriate.