The original movie was actually pretty dark, not the Smooze movie, the one before it that no one ever seems to remember. "Escape From Midnight Castle". There's even a quite terrifying(to tiny elementary school Tara) scene where some of the ponies get transformed into hideous dragon monsters and are forced to pull the bad guy's chariot of darkness.
But ya, the new movies and the entire cartoon series.... BLEAH! You need insulin just to watch it. And they outsourced their animation crew or something... the look of the ponies and the quality of the cartoon went WAY down after the first movie.