This is not to say that I must think as a child as I approach a book for a younger audience. No, I need to do what Donna Norton exhorts in her textbook: I need to read through the eyes of a child, see the possibilities of the book through the eyes of a child. But that does not mean that the adult part of me might not see some other things. I know there are picture books, that like some Disney movies, have content that older readers might "get" that younger ones might miss.
I know that when I read a MG or YA book, I have the same challenge: to read through their eyes. It does not mean that I turn off the adult portion of my brain. I can't. But there is still a part of that inner tween and teen that "gets" it, too. I finished reading MAXI'S SECRETS last week with tears streaming. Ditto so many books. We who love books often tell stories of what happens when we read sad books in a public place and have people show concern for our tears. And the same is true for books that have great good humor. I remember reading an early ARC of a Rob Thomas (the author, not the rocker) novel and looking up to see folks staring at me because I was laughing out loud.
I think those of us who love books for kids can tap that inner child readily, can see through their eyes, can "get" it.