Peter Jackson wrote:[W]e started to .... expand it, because The Hobbit; you know Tolkien wrote The Hobbit before he wrote Lord of the Rings .... But then once he wrote Lord of the Rings he naturally expanded the world and the events that were happening in the background of The Hobbit. Things that he didn't really know about when he was writing The Hobbit but he devised later on when the world of Middle-earth kinda grew in his imagination. There's a lot of material that we can retrospectively put into The Hobbit which doesn't actually exist in the novel; which is fun, I mean this is fun stuff, because it sort of expands The Hobbit in a way that makes it very much related to The Lord of the Rings.
My bold emphasis.
I'm wondering what everyone thinks about this. Personally I think that they should just focus on making The Hobbit, but it seems that they want to make it a general prequel to The Lord of the Rings instead.