Could this have anything to do with our culture's fascination with cunning, charming, arrogant characters without much of a moral compass? (Wait, is that actually culture-specific, or are tricksters typically sympathetic?)

Given the evidence for psychopaths’ dominant response styles and differing response thresholds, increasing the salience and consistency of punishments would be important elements in these interventions.

I would say the exact opposite! Drop the punishments since those don't work well, and reward desired behaviors instead.

Holy moly, freaky theory: The old parenting style of punishing children when they misbehave and ignoring them the rest of the time produces obedient children in a population with low psychopathic traits, but children good at manipulating parents otherwise. When the population becomes more psychopathic (possibly due to this; in general I'd expect more social and reproductive success from good manipulators with little care for social norms, though impulsiveness may compensate), rewarding children for good behavior works better. Do we know where the parenting style shift came from?