Unless there is more to it, I think it's because it appears to be set completely within the city limits so it loses the remoteness of travelling through a sparesly populated wasteland and finding the odd settlement where people are struggling to get by making houses out of whatever they can find lying around. Cities definately have their place in the Fallout world but like the wastelands they should be sparesly populated and not sole focus. There should be more to do besides it. The best times I've had in the Fallout world has been out in the wasteland feeling a real sense of being alone, scrounging through the odd burnt out/falling apart building for supplies, finding clues to the lives of their former owners and wondering what happened to them. Loved Fallout: New Vegas for this as the desert setting was perfect for me and New Vegas, while it was the main storyline, was almost like it was just another rather large outpost in an otherwise vast wasteland.