It is more like a personal wish of mine to finally experience a life inside the vault for much longer that just an intro sequence. Maybe it's because yet another Fallout from BGS ruined the wasteland for me. That's why I want to get back underground to salvage my last post-apocalyptic dream.
Ever since first Fallout game was released, the series focus on portraying the post-nuclear war period of the setting. And rightly so - after all Fallout games are made as post-apocalyptic RPGs (what?!). Pre-war times are rather uninteresting for me, so I'm glad we only experience those through intros or opening sequence.
But what Fallout series (especially the modern games, which have the required technology) neglected is the period between entering the vault and getting out to explore the wasteland. It is a most interesting period for me, prolonged isolation and psychosis, being aware of the nuclear holocaust on the surface, dealing with whatever sinister experiment Vault-Tec prepared for the vault dwellers. This makes a perfect setting for at least a part of game for me!
Fallout 1 and 4 managed to get close to this idea. In Fallout 1 you always had this one special place to return to, a safe, reliable and clean place where you could rest. Even if it was only for the sake of roleplaying, there were no survival and settlement managing regarding Vault 13 in Fallout 1. You had to find the chip for the Vault to survive and that was it. Fallout 4 on the other hand managed to grasp something else - Vault 81 (spoilers ahead), after completing the quest you are given the chance to stay in the vault and live inside your own quarter. Which is cool. But still - no workshop, no more quests, no managing. You've only got a bed where you can sleep and place to store stuff.
What I'd love to see is a merge of those two ideas. You start the game and begin your life in the vault, pick a profession maybe, do some work for a few first days. But you can clearly see from the get-go that conditions are harsh, supplies are low, something is clearly wrong - maybe Vault-Tec left you with only 20-40 years worth of food and water? How the overseer will respond to this crysis? And then the game introduces you to the wasteland, but still - the vault is still there, people inside trying to survive and they are counting on you to help them. Maybe later you could help them to establish a settlement outside the vault? But what about the raiders? Maybe someone will try to hire Gunners to raid the vault for precious technology? Maybe BoS will see vault dwellers unworthy of using pre-war tech? Just let us experience the early struggles of the vault dweller! Opportunities are infinite here.
But instead we got a frozen graveyard under ground, to which you return to only to pick up the Cyrolator or gaze at your dead spouse.