Yes, Vaults can't have elevators because you don't want them to.
And they are very slow, can only fit 5 people, and are only used the very minute nukes are launched.
I get it, they can be in the game, and they are in the game. I am not disputing the reality of the game, as presented to us. I am disagreeing with it. Strongly.
It's normal speed for an elevator thing that size, can likely fit more than 5 and why would they load them up when they didn't think anything would happen?
Hahaha, because thats why they built them in the first place, to fit 1000 people, in case of a nuclear attack
And there it is - the nuclear attack.
Nuclear attacks are typically not agreed upon events, so... the surprise is part of the deal. They must have known that when building it, but there we go!
Slow-ass elevator, can fit 5 people. Way to go!
Spell-it-out-time: the reason they re-designed the whole system, is because all prior games - including FO3, shows that the vault entries are inside a deep tunnel. People will congregate here - even clogging up the tunnel ("let us in!"-signs outside Vault 101), but this wouldn't be AWESOME playing experience.
They sat down and thought long and hard - how to show BOTH the vault and Teh Awesome? I KNOW! Make the vault entrance right on top of the surface, right where the nuclear blast will tear through everything!
"But... won't that make the blast like bake the actual vault door?" "Hmmm"
And then they thought of the elevator.
It makes NO practical sense.
It makes plenty of AWESOME sense.