It is! Ende was raised under the esoteric Anthroposophy philosophy, and I suspect much of his works are dedicated to debunk its nonsensical beliefs. The second half of The Neverending Story is a philosophical treaty on itself (it hurts the book as an action story, but gives you a lot to ponder about).
His child books certainly have a deep second reading as adults.
His child books certainly have a deep second reading as adults.