I find it very hard to believe that anyone over the age of 12 would read these books.
What? You've never read LoTR? Or anything in the fantasy genre? There are a lot of angles to enjoy the books from. Everyone can get something out of it. You don't have to be physically a kid.
Haven't you ever heard of the phrase "a child at heart?"
I guess I was just blessed (or cursed) with a huge amount of imagination, but I find it difficult to really enjoy books that are not in the sci-fi/fantasy/horror genres.
There are some exceptions (Dean Koontz, for example, but he often uses supernatural/sci-fi elements in his stories, and some of the earlier Tom Clancy books were good). However, unless a general fiction book is very well-written, I tend to find them extremely boring.
I don't want to read about reality, I read to escape from reality. But maybe that's just me.