Right.
Like if people took up arms in the remnants of a posh, fancy, http://fallout.wikia.com/wiki/Tenpenny_Tower...they wouldn't automatically start wearing suits and acting as though they're distinguished socialites.
Or if people were holed up in a http://fallout.wikia.com/wiki/Cathedral, they wouldn't automatically take up religious lifestyles.
OR HEY, just to be COMPLETELY out there....
If a bunch of people were holed up in the remains of a http://fallout.wikia.com/wiki/New_Reno, they would certainly not start anything involving http://fallout.wikia.com/wiki/Made_Man, yes I said http://fallout.wikia.com/wiki/Tommy_Gun, or any of that junk.
Yes, part of it is that it's devastated. But another is that the Fallout world contains EXAGGERATIONS. There's no logical reason that the New Reno gangs are so mobster-like in attitude and style other than to play our expectations and to have a little fun with it. If the Fallout series started taking itself seriously now, I think I'd start having a problem or two with it.
As I understand it Allistair was the influence on Tenpenny tower, he did name it after himself, afterall. He may have settled there because it suited his tastes. As for how he, a man of the finer things, who traveled all the way from England, became very wealthy and came across such a well preserved tower of pretentious excellence before anyone else, is probably something you should be grilling the devs about if you don't agree with its consistency.
The Cathedral is an easy one. Very easy in fact. Too easy for me to begin to comment on...oh alright, just this once. Richard Grey was exiled from Vault City for murder, and went on an expedition to Mariposa military base with none other than Harold himself, a little more human back then, and some other guy who's name eludes me. Richard was thrown into a vat of FEV and become essentially a mass of biological matter, which then preceded to 'absorb' the consciousness of organic and cybernetic matter alike, through this networking he discovered the location of a fake vault, meant for public demonstration, he travelled there and setup operations, followed there by his many cultists, they built the cathedral around the vault itself. The cathedral was a result of cultist influence. Not the other way around. And was very much a post-war product. C'mon dude

We've already discussed how New Reno made little sense within the Fallout universe, an inconsistency some original devs have since held their hands up to, but it's been done, it can't be retracted. Although the preservation of Reno would make any mafia influence present in the city amplified by the destruction and offset the legal balance around Reno.
Fallout 2 didn't take itself seriously enough, I personally didn't mind this, I liked it even, but it doesn't make it any less true, a little return to form with FO1s atmosphere would work, humor is of course, completely secondary.
My orignal point still remains.