Much like earlier Obsidian game Knights of the Old Republic 2, what we got in Fallout: New Vegas was only part of what was planned, or even implemented only to be dummied out. Modders to the rescue! Investigating the source with forensic care , there are now many fixes available to do everything from turn Freeside back into the single map it was meant to be, to adding back characters that were cut. Better still, you can grab the necessary mods in a set of easy packages - right here!
There are more changes still to be made, but the ones on offer so far include full quests, missing characters, an in-engine version of the introduction, and several packs containing small changes that don't warrant their own full mods. Check the descriptions for compatibility information though, as a few apparently don't play well together (a Brahmin companion called Betsy and the new Open Freeside being the most obvious.) Head over here for a preview of what might be coming back later.