It's been 204/203 years since the bombs dropped and Vegas was never hit.
It's perfectly logical why it shouldn't look like the bombs dropped a week ago.
If whole world is pretty much wiped out with nuclear bombs - it will take millenniums before civilizations can recover.
And first few centuries things indeed gets worse. Most resources are imported nowadays - so after nuclear apocalyptic "ordinary" life can't flourish because of lacking resources.
I really hope that developers has understood that post apocalyptic feeling was the key of success FO3 got. But as I already mentioned I'm afraid NV might be an disappointment for me. I was kind of abashed when I first understood that they are focusing e.g Casino gaming ...
I just can't understand why anyone would like to play "playing" in a casino - If I like to gamble I just visit some real casino....
As Albert Einstein said:
"I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones."
So, if this game is some kind of "red dead redemption" with possibility of virtual gambling - I will just hate it.