I'm for admitting highly-skilled immigrants, and I think they're preferable to unskilled immigrants. I think you can make all sorts of arguments about the societies of origin losing out, which means that somewhere, down the road, we have to spend more dollars propping them up, and about how it creates more competition for native workers, but I still think the advantages to the receiving society outweigh the disadvantages. The CBO has studied the issue, and their conclusion is that the US receives a net benefit with a more liberal visa plan. A Notre Dame economist has also looked at the effect of highly-skilled immigration on US cities and found that there is some difference between the impact upon the native low-skilled and native high-skilled populations, but the longer-term impact wasn't conclusive. Apparently other trends tend to obscure the effect of immigration in the longer term. See
http://nd.edu/~awaggone/papers/wozniak_murray_JUE.pdfThe short term disadvantage is that many immigrants face significant hurdles when they arrive because of poor language skills, or because their academic credentials not recognized here. A Brookings Institute study found that half of the highly skilled are working in jobs they are overqualified for. Apparently many of them must spend years being recertified before being allowed to work in their chosen fields in the United States. I know people in this situation. This has the effect of displacing some mid- to low-skilled native workers. (I know a woman from Bangladesh who has a master's degree in pharmacy who works as a cashier at Wal-Mart.) If you take that into consideration with the Notre Dame study, you can see it as a short-term problem.
My feeling is that despite temporary disequilibria, the receiving country is generally better off economically down the road when it admits highly educated workers than it would be otherwise. The Bengali woman to which I referred has three daughters, one of whom is about to graduate from medical school and has a research career lined up at Mayo, another of whom has been accepted into an engineering undergrad program. Of course, each of these daughters displaced some potential student who might have been accepted into those positions, but the universe has a limited number of really good engineers and I'm glad to receive them.)
Just my 2c.
