Vault Dwellers
Perhaps the best way to explain why the United States of 2077 perished in atomic fire is to simply review the vaults they left behind... sadistic experimental time capsules that put greed for power above their responsibility to the future.
Even today, there are still unexplored vaults that have remained dormant for over two hundred years...
The Squandered Future
While most vaults from the Pre-War corporation "Vault-Tec" were social experiments designed to accumulate data on how to more perfectly control human beings in the post-war future... some were designed merely as "control vaults". These control vaults still broke down and eventually opened or killed their occupants, but their was no intentional sabotage per-se.
Survivors of these underground time-capsules still emerge occasionally... dressed in the iconic blue jumpsuits. They are usually picked off by raiders quickly, as their upbringing underground has ill prepared them for the hazards of the Wasteland.
There have been cases where Vault Dwellers have emerged en-masse or in small groups and managed to survive and create small communities. Indeed, a very few vaults were designed to do exactly this and even given highly experimental terraforming technology such as the G.E.C.K.
If only Vault-Tec, the federal government, or the Enclave had taken the vault's public facing mandate of preserving civilization more seriously... or less cynically... then perhaps they would have succeeded.
So I suppose I should address the elephant in the room... where is the yellow trim? I hate painting yellow... so I just skipped it! One day I think I'll go back and apply a gold metalic to the trim instead of yellow and that will be enough... for now... they'll just have to make do with their all-blue jumpers!
The models I have for Vault Dwellers at the moment is pretty limited, so I painted a "Nate" with a Laser-Musket arm, a "Nora"... and then took a PVC Nora, sliced off her head and 10MM pistol and replaced with a resin laser rifle and Flight Helmet. The laser rifle is a big large and ungainly but I like it enough and I didn't have another option at the time.
I could have used more flight suit BOS figures for Vault Dwellers, but I chose to use them for my Gearhead Gang members instead. With a dog and Mr. Handy it's easy to flesh out a small gang of Vault Dwellers to explore the wastes anyways!
In terms of storytelling, obviously the Vaults as social experiments provide an endless source for horror, fun, and dungeon crawling... but a big part of me wishes that one or more of the Fallout games explored a sincere attempt to rebuild by a Vault. Basically... I wish the newer Fallouts had more "Vault City" and (a little) less "Gaaarrrrryyyyyy?!!"