You can't ignore the social cost of integrating and Americanizing new immigrants. You also can't brush aside the potential load in the social welfare system. The economic cost of immigration tends to be low, but that's partly because we mostly deny welfare services to poor immigrants. Having a class of people living here without a safety net, or being limited in your ability to expand the safety net for everyone is a bad thing, not a good one.
The system is already setup to favor younger and healthy individuals with higher education. To get GC you have to pass medical exams including AIDS test and so on.
