I think Thomas' "letter" seems very tongue in cheek, and I doubt if he was being serious at all when he wrote it. But I didn't expect this movie to be anything special, even when I first heard it was being made, and that was at least 5 years ago. From what I've read in various reviews, it seems like the creator of the movie (Matt Groening?) wanted to skip the humour side of things and give everyone some good old Springfield soft core pr0n.