And when the witch sends them en masse after Dorothy and friends and they darken the sky with their numbers, well, any kid who had nightmares knew exactly what caused them.
Why does adding wings make them the worst thing this side of Freddy Krueger? They're unnatural, of course, and just creepy. Monkeys, eh, not the most frightening member of the animal kingdom. It doesn't seem that terrifying when you write it down.
