C'mon Bethesda. Its stupid.
It's all about priorities.
That are likely many places where your reaction to them will change over time.
However, this is a game where you can spend a long time doing other stuff, so it is important that things don't time out.
Your companions will comment on 'Nate/Nora' if you go back, so some consideration has been given.
As has dialogue changes when you do quests in an unconventional order.
And if you don't want want to comment on the dead bodies, you don't have to activate the bodies again.
Honestly, this seems fairly trivial criticism in my view.
Oh, and inb4 'modders will fix it'...
I like it the way it is. I think people would be less inclined to just wonder around exploring and adventuring if an important quest you wanted to do but got distracted from suddenly failed because you hadn't got around to it yet.
It's made fairly clear from the moment you enter Vault 81 that's it's a full time effort for the inhabitants to keep the existing part of the vault running, let alone having the time, energy and resources to start repairing the other section.
And why would they bother ? There's no overcrowding, and the derelict section doesn't seem to offer anything they really need.
It's possible a decision could be made to slowly increase the population size and create additional accommodation and facilities in the derelict half, but that would likely be a long term project, beyond the scope of the game.
Yeah It would be good if more of the dialog changed as time went on to reflect how your progressing, rumors of things you've done etc.