I agree wholeheartedly with Becker about the desirability of our accepting more skilled immigrants for permanent residence. Of course, the more that are accepted, the lower the average quality. The qualities of skilled immigrants that Becker rightly praises are a function of the size of the skilled-immigrant quotas; the lower the quotas, the more outstanding the successful applicant is likely to be. But it is a safe bet that the quotas would have to be much higher before a discernible fall in average quality was detectable.
The most difficult issue relates to the security concerns that Becker touches on, which I discuss at the end of this comment.
I think there is a simple answer to the "brain drain" problem. For concreteness, consider immigration to the United States of Indian software engineers. The more who immigrate, reducing the supply of Indian software engineers to Indian software producers, the higher the wages of those engineers in India. This will tend both to reduce the numbers immigrating to the United States and to elicit a greater supply of engineers for the Indian market.
I am puzzled by the political opposition to increasing the quotas for highly skilled immigrants. The average worker is benefited by immigrants who have skills much greater than his own, because they increase U.S. productivity (so the average worker benefits as a consumer and he may even benefit as a worker if his employer's greater productivity increases the employer's demand for workers) and he does not compete with them; they are in different job categories. And as Becker points out, restricting immigration of highly skilled workers increases the incentive of U.S. firms to outsource production to countries containing such workers; and outsourcing, by exporting jobs, harms the employees of those firms. So I would not expect unions, or average Americans, to oppose the immigration of the highly skilled. Maybe firms that compete with employers that utilize skilled immigrant workers most efficiently oppose such immigration; maybe universities as well, because, as Becker mentions, the more skilled immigrants there are, the weaker the demand of nonimmigrant Americans for scientific and technical education. Hiring skilled immigrants is a way of outsourcing such education.
One way to reduce opposition to such immigration would be to insist on a somewhat higher skill level of applicants for skilled-worker visas. The higher the required level, the fewer nonimmigrant Americans will be affected by the immigration of skilled workers. There are three principal employment-based immigration categories for greencard applicants (as opposed to the H1B program for temporary employment). The top two, EB1 and 2, set very high standards, but the third, EB3, is very loose: it "is for aliens with bachelor's degrees, but who do not qualify for the EB2 category, skilled workers with at least two years of training or experience, and unskilled workers. An alien in the bachelor's degrees category must demonstrate that he or she has a bachelor's degree or equivalent, that a bachelor's degree is required for the position, and that he or she is a member of the profession." Oddly the same annual quota--40,000 visas--is fixed for each of the three categories. If the first two quotas were increased, and the criteria for the third tightened up, perhaps by specifying particular industries, such as high-tech, in which the applicant could work, the impact on nonimmigrant American workers would be reduced.
I would not describe as "profiling" a system of screening would-be immigrants that, without fixing quotas on a national basis, screens more carefully applicants from nations that are breeding grounds of terrorists. The efficacy of such screening is another matter; the less effective it is, the stronger is the argument for reducing skilled-worker immigration from countries in which terrorists are admired and recruited. Besides terrorists, we have to worry about spies from potentially hostile nations; this implies a need for careful screening of Chinese immigrants as well.