Tim Cain, co-creator of the original Fallout back in 1997, has revealed the real reason that the Vaults were created.
In a new episode of his YouTube series Cain on Games, Cain explains that the Vaults were initially created for more than just ensuring humanity could repopulate the Earth. When designing the Vaults, "the head of the Enclave and the highest levels of government were like 'let's build a starship, and take it to nearby stars.' But that would take forever, so it has to be a multi-generational starship, and the only technology we know how to build is atomic power. So we can make an atomic power plant that would help us build a starship for hundreds of years, but we don't know how to do anything else. So the Vault-Tec director, not being a great person, says 'why don't we use the vaults to figure out the technology we'll need on the ship?'"
So, as you may have guessed through playing the games, each Vault was not only designed to keep people alive but it was also created to test out a different piece of experimental technology that could help humanity's great emigration to the stars.
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"I always thought the vault that made Vault City in Fallout 2 was a control vault," Cain continued. "It was designed to do everything right. It gave Vault-Tec a purpose beyond just 'let's save some of the American population then release them back into a radioactive dead zone.' That's the thing that doesn't make any sense. Making the vaults technological, experimental beds with a purpose towards making a multi-generational starship to take our best and brightest away from Earth if there's a nuclear war - that made sense."
What do you think of the real reason why the Vaults were created in Fallout?