Ursula Le Guin has a truly phenomenal essay about fantasy and children’s literature in the New Statesman. I highly encourage you to read the entire piece. The conclusion:
The Harry Potter phenomenon, a fantasy aimed at sub-teenagers becoming a great best-seller among adults, confirmed that fantasy builds a two-way bridge across the generation gaps. Adults trying to explain their enthusiasm told me: "I haven’t read anything like that since I was ten!" And I think this was simply true. Discouraged by critical prejudice, rigid segregation of books by age and genre, and unconscious maturismo, many people literally hadn’t read any imaginative literature since childhood. Rapid, immense success made this book respectable, indeed obligatory, reading. So they read it, and rediscovered the pleasure of reading fantasy – which may be inferior only to the pleasure of rereading it.