America is the land of opportunity, and someone's opportunities should not be limited simply because they were born halfway across the world.
It should be far easier to immigrate to the United States, and far easier to become a citizen. The process should not take more than a year at most.
Someone spends 365 days in the US, moves back abroad, and the US government should go to the end of the Earth to help them? Work in government jobs, potentially sensitive in nature? Serve on a jury or run for office with their entire year of experience observing life in America?
At that point, you might as well just give everyone in the world US citizenship.