I think if it was just supposed to be "little girl does f*cked up things" then they probably would have speeded up the dull exposition and gone straight to the torture, maybe even added a few more kills at the start, and skipped the sermonising.
But ok, if that is the films only intention, which I doubt, then the only pretentiousness comes from the hundreRAB of internet reviewers who have apparently mistaken a creepy "thrill ride" for something much deeper.