The whole first theory is literally the entire beginning of Fallout 3 after you leave 101. There's a town called Megaton that has little to know weaponry, you can help with its defenses (disarming the bomb, fixing the pipes, etc.), Moira tells you to go out and see if food is scavengable at Super Duper Mart, and a whole [censored] ton of other stuff.
And, technically, you do have to leave your vault due to technical difficulties. When Dad opens the door, the roaches probably screw up the wiring, which might be the cause of why all the electronics were somewhat on the fritz when you have to go back into the Vault on the "Trouble on the Homefront" quest.
I know what you're getting at, but pretty much, what you're suggesting has already been done. I'd advice that you'd make your own mod of your ideas, but there's indefinately not going to be another game with what Bethesda already did with F3.
Yeah its just an idea , Honestly though I would rather see newer creatures like say there was a research facility that had a problem and caused some of its subjects to evolve like a werewolf , where one of the researchers had been bitten by a wolf they had as a subject and when the bombs fell the radition exposure created a side effect where the man had been turned into a were wolf ha just saying . I am just tired of seeing robots being the center of the research , its sad but I am sure soon enough robots will start to replace humanity both on the frontlines and in the factories in larger scale.
Lol, ever hear of Being One? If not, google it. Something in the third part of the game it talks about how there was some virus that spread from the moon when it got nuked for some reason that made people turn into abominations that were dog-like (a.k.a. werewolves). Try something like that.