How do you figure Fo2 didn't have a 50's or 60's vibe with New Reno? It obviously wasn't as pronounced but the vibe was sure as shit classic gambling town schtick. It was rougher, but FO3 and FO3:NV also take place after the fact where the major centers are coming more up to speed as well.
My big problem wiht FO3 and NV is how they deal with the BOS. Which IMO would have grown susbstantially in those sorts of circumstances and not diminish. Hell, I'd still like to see a BOS focused game in the FO universe.