Spoilers about GOS3 below
While the brain rotted fan fic lover in me is bereft at the lack of physical intimacy in GOS3, I am reminded of my AP history professor's reminder to look at the original documents.
Book! Omens was primarily written by Pratchett, not that other author. I think a computer style writing analysis even suggested around 70% or so? With that other author (mostly) out of the picture, we should expect to see the pendulum swing back from GOS2 more to the style of Terry Pratchett. And Terry Pratchett was very well known for 1) lack of physical/sexual intimacy in his writing, keeping it to allusions or off stage references, and 2) his profound humanism.
This is a very humanist ending. It is in keeping with the Book! Omens concepts that the only thing the angel and the demon loved more than each other was the world, Heaven & Hell behaving like two children's gangs running amok over Earth was actually not good for Earth or it's inhabitants, and free will, genuine free will, is a good thing.
We get books, and gardens, and the universe. And love. We get love.
