They cut out massive amounts of content to meet ship dates. Because it was a launch game for the Xbox, the date was absolutely set in stone, and furthermore, they didn't even set the date in the first place. So Bungie had to push to finish a game when in all reality they needed 6-12 months longer. I've seen several documentaries where dev leads at Bungie expressed this sentiments. Three major examples of the content cut that I've read about are: 1) The arrows on the floor in campaign: Bungie hated that they had to cut corners and direct player flow with actual arrows, but it was a necessary evil 2) The re-use of the same level for both AotCR and TB 3) The massive re-use of textures and environments (e.g. all the rooms looking the same)