I am under suspicions that you are a troll sir. That, or you are the worlds worst critic.
I can actually knock down your argument with just one statement. If the game is a direct copy and paste (Which it's not. It's not even a crips texture replacement of New Vegas. They're using completely different sharers. Fallout 3 and New Vegas couldn't look dark if you painted the world black) they did it for size reasons. Have you ever tried decompressing an ENTIRE bethesda game? It's a LOT larger than the 12gigs it's taking up on your rig. Reuse is something that is more common than you are giving credit for.