Can somebody tell me why this is such a big deal and why the dev's/publishers are so tight lipped about this stuff?

Does it have to do with the way the projects and production cycles are funded? Or more for an overinflated sense of self on behalf of the publishers that they are the only ones that know how to truly 'market' a game. This seems really silly. If you're making fable 3, fine, why the secrecy...