I always thought the original was pretty dark already.
I mean in this one movie you have the following:
child abduction by flying monkeys
assault by talking trees
one character is set on fire
that same character is torn in two
threats to drown a dog in a river
another character melts right in front of your eyes
one character is crushed by a house with nothing but her feet sticking out from underneath
oh and witchcraft, lots of witchcraft
Folks, the only thing missing was the blood and that's only because it was 1939. Still, not exactly childish fare.