Daniel Kuehn, Noah Smith, and others, are discussing immigration policy. I have not read all the relevant posts, but from what I understand Smith is looking for immigration reform in favor of higher skill migrants and Daniel is not in favor of “subsidizing” one for the other. For Daniel, low skill labor is just as useful and needed. I think I agree more with Daniel.
Moreover, what does the data about high skill immigration really say? There are foreigners who receive high levels of education in the United States and return to their home countries. Current immigration policy also makes it much easier for high skill immigrants to gain permanent legal residency (maybe not as prioritized as family reunification, but far easier than other low-skill immigration — they have essentially no recourse for legal permanent residency and existing work permits are horribly designed). But, some highly skilled foreigners make enough in their home countries to induce them to stay. It is not all about income; there are other considerations people make before deciding to migrate (or before even deciding to think about migration).
I am sure that there are many highly skilled immigrants who cannot gain permanent legal residency (mostly because they cannot find sponsors). But, is it bad enough to prioritize reforming immigration policy that affects only these types of migrants? I am not so sure.