Remember, that all drama is based on conflict. That is why parent against child, child against parent is so powerful in theater and film. Nothing unusual in that. And why “Long Day’s Journey Into Night” is still considered America’s greatest contribution to theater.
Many classic films of Disney were very powerful and had very dark imagery - Dumbo’s mother, Bambi’s mother, Pollyanna turning against the town after her injury...all great stuff of drama. And all happily healed by the end.
^^THIS
At around age 13-14 or so, teens NEED to separate from their parents. Themes of the wicked stepmother, the hidden royal birth, the sudden access to magical powers all speak to this innate need. Teens, especially females, it seems, are drawn to reams of this sort of material, as evidenced by the YA fantasy novels that always incorporate the same memes. Males seek out stories of heroism, romantic sacrifice that wins the desirable female,successful quests and universe-changing invention, but they are responding to similar needs to separate from their parents, escape the emasculating feminine and reclaim masculine domination from their aging fathers.
By 18+, into the 30s or even later, the meme is the perfect mate. Enter the romance novel or the chick flick. A mash-up with the earlier themes gives birth to the erotic fantasy genre. There are sub-genres: werewolves (-bears, -cats, -dragons) and, of course, the fantastically popular vampires. Boys graduate to adventure stories, military themes of conquest and domination.
Blame human psychology. Disney and the successful authors/publishers are responding to a perennial niche market. The original Brothers Grimm compilations of ancient folklore were devoted to the same themes, culturally appropriate for their time.
The basic story is: fear, pain (and more fear and pain), then triumphant catharsis. We humans crave these stories, so someone will always provide them.
The scene of Dumbo saying good bye to his mother still makes me cry.