Yeah. This is why people like anime; Japan, unlike the vast majority of people in the west (the only exceptions are Pixar's films, Avatar: The Last Airbender, Batman: The Animated Series, and possibly a few others), sees animation as the legitimate storytelling medium it is. Of course cartoons can be mature; there is absolutely no inherent reason why they cannot. It just takes a culture with a shred of artistic sensibility to see it.