The Nature of Journey in Story as seen in The Mysterious Benedict Society

I have noticed that in any good work of children's fiction there is some sort of physical journey to be had. Adult fiction deals with different journeys, into the heart or the mind or the soul; children's stories almost always are consistently physical journeys. An example of this is The Mysterious Benedict Society trilogy. In each book, they travel to a different place, and it's clear that the journeys are just as important, if not more, than the destinations. I think that physical journeys are the best way to write stories, because in the physical journeying the other journeys - emotional, spiritual, mental - also come out in that context.