However, this completely neglects the potential cultural and political aspects. Immigration, particularly in large amounts, will dramatically change the cultural and political face of the US. We need to account for these changes before making decisions on immigration.
A highly educated, self-sufficient and productive person said this: "I'm gradually beginning to feel that we Chinese need to be controlled. If we're not being controlled, we'll just do what we want."
If we import 50 million such people, the "parochialism" we discard may well be democracy and freedom.
(source: http://en.wikipedia.org/wiki/Jackie_Chan#Comments_during_200... ). This is one example that springs to mind, and is (I hope) fairly non-controversial.
In the end, any system which would disqualify a Shockley is a broken system which will bankrupt the tech industry.
Don't forget: they might be xenophobic too! Or do we need more xenophobia to protect "democracy and freedom"?
I would welcome Jackie Chan if he sought US citizenship, regardless of any peculiar political comments. Peculiar political beliefs are allowed; it's an explicit feature of the American system.
Any number of "Jackie Chans", when mixed in with all other top-performing immigrants with diverse beliefs, total up to zero chance of making make our society coarser or less free. Highly-productive people who leave their country of birth because they prefer the USA are not, as a general class, small-minded enemies of democracy and freedom.
And even where they have some preferences we natives might find peculiar, within one generation, those peculiarities will either prove their enduring value or be discarded by the children raised here.
As it has been for hundreds of years, so it shall be.
And thanks to American cultural/business exports, telecommunications, the rise of worldwide English, and rising world living standards, each wave of immigrants is already more like us, upon arrival, than previous waves were.
The fact is, some smart and productive foreigners display values which are incompatible with ours. I've met a few. Maybe their numbers are few enough so that it doesn't matter. But such a claim requires evidence beyond vague handwaving.
Note: I'm not arguing against immigration. I'm only arguing for evaluating immigration on all possible dimensions (including cultural and political), not simply economics.