Well it depends if you live in the US or you live in a country that is hemorrhaging your best workers to the US. No idea why you are trying to lump both groups together as if they should both have a single opinion.

People in the U.S. used to complain that we drain the rest of the world's brains. That has stopped. I was referring to that.

If you put yourself in the shoes of people in other nations, then... a) individuals might really like the option of emigrating to the U.S., but b) their nation might be better off with them staying at home. Interests conflict. The question is whether we should have selfish policies (such as putting a company's bottom-line ahead of a nation's, or one nation's development ahead of another) or not, and, of course, which is is which because one could argue that the only ones being selfish are the Americans who object to all these visas (I don't think they would be the _only_ ones being selfish, and arguably the 'nation' exists in part to protect its citizens, but yes, this is a case of selfishness).