It would have been cool if New Vegas let you go to some of the western areas from Fallout 2, sort of like how Fallout 2 let you go to a few of the northern areas from FO1. Like New Reno or Vault city. Maybe if the game had more development time. The cancelled Van Buren had Hoover Dam as a location. Weird that Vegas wasn’t listed as a planned location. Maybe it was planned though. Stuff like New Canaan was there too. A few areas you visit in the DLC of NV.
I think a more realistic expectation at the time as to why those areas aren’t explicitly in the game is a memory/space problem. Though maybe more dev time would have helped. But New Vegas is choked by issues inherent to literally the council generation of its time. You notice it more or exclusively in PC than you would have on the Xbox360 or PS3. Like the game’s issue with handling memory and its tendency to CTD is because it’s fully expecting to boot from a DVD and it wouldn’t have to store so much memory at any one time.
Perhaps they could have revisited those areas with DLC, but the DLC philosophy at the time was much different as it is today. Now a days the market strategy with large titles is to treat them all as live service experiences where you release large numbers of low-ish cost DLC and management updates until the actual replacement goes into production.