To be added to.
I feel it important to say, I believe "opposites" are merely things that are the same that exhibit different traits based on time.
These two archetypes of stories seem to reflect ideas of masculinity versus femininity, action versus creation, extroversion versus introversion. The Hero's Journey is an exploration of the world, with aspects almost a kin to manifest destiny. "Rid the world of evil" which throughout human explorative history seems to be a metaphor for turning the unknown into familiar (often through the extermination of anything non-familiar). But "falling down the rabbit hole" stories, which I use to name stories of characters, predominantly adolescent women, who unknowingly "fall" into another world, seems to be a metaphor of the exploration of oneself. An inward journey in contrast to outside journey.