To be fair to Von Daniken, he succeeded in sparking the imagination of a generation of children in a way that most children's literature never managed. That he was later proven to be a fraud is arguably far less important (that's my own view; others obviously feel the fraudulent nature of his work overshadows all else - and that's a valid viewpoint too).
I think it was Chariots of the Gods that had a photo of an object von Daniken claimed was an electric battery many thousands of years old. I can safely say that photo, by itself, helped enrich my childhood and sent my mind soaring to fantastical places.
Not defending the guy or his methods. Just saying they had positive side-effects.