"I, too, have long been perplexed by these questions. A "nation of immigrants" should be mostly immigrants, no?"
It's time to take it to the next level then, and make America truly a nation of immigrants. For starters, everyone born here would have to leave. Then they would be replaced with immigrants. And when the immigrants wanted to have kids, they would have to leave the country and start their families elsewhere, lest their kids be born here and miss out on the magic of immigrating here.
So America would be a place where people came, worked for a few years, then moved on. Sort of like one of those extended stay business hotels. The United States of Extended Stay America.
Sounds like a plan!
There's a lot of money to be made off of constant churn. These days, the question that's in the forefront of everbody's thoughts is: "Is it good for the billionaires?" Anybody who isn't worried about the welfare of our precious billionaire resources is A) Not currently a billionaire himself, B) Obviously, never going to be a billionaire, and therefore C) A loser.
My favorite book of 2011 was Homesickness: An American History by Susan J. Matt. This academic gypsy historian, who finally earned tenure at the sixth college she was employed by, draws an insightful distinction between homesickness, which was indulged during the 19th Century but is derided these days because it's too particularist to make much money off of (you're homesick for Palmdale the way it was in 1981? Sorry, can't do much for you), versus nostalgia (you liked the Go-Gos when you were growing up Palmdale in 1981? Well, that's why we licensed "We've Got the Beat" for Target's Back-to-School-Days ads!)