Here's the relevant part from the letter sent to congs.
"Teach Us Book: The first provision is a new 224-page publication entitled What Can the Bible Teach Us? It is based on the book What Does the Bible Really Teach? The Teach Us book does not replace the Bible Teach book. Rather, it will be useful when studying with individuals who need to have the truth presented in a simpler manner. "
So it's really not surprising at all that the book is aimed at a low reading level.