They did release over 2 gigs of files in the weeks before the expansion, them packaging the basic terrain which is usually one of the first completed assets on the disc is about efficiency, not ripping off the consumer. Neither you nor I was involved in any of the design meetings nor do we have any 1st hand insight into how many iterations and variations the story took before it was decided on. If you want to believe that Destiny was gutted prior to release and that we didn't get what we should have I doubt there is much I can do to change your mind. That being said there is nothing in the way of actual evidence that makes this theory more likely than the simple explanation we've already gotten from Bungie with regards to on-disc content.