This is fine for the purpose you are outlining, but it completely neglects the fact that the primary reason people are emigrating from their home countries is seeking a better quality of life for themselves and/or their families. Closing the door to them shuts them out from this path.
Moreover, a lot of immigrants that arrive to the US end up having a greater impact on the world as a whole than they would or could have had in their home countries. This is the ideal scenarios of the sometimes true concept, "Land of Opportunity". I don't presume you are ignorant of this, but conditions in many other countries are worse for a lot of reasons.
My own anecdotal evidence: One of the main factors the lead to my own father's emigration from his home country was because the "old guard" at his university effectively blocked him from progressing any further lest it be a threat to their own established position. Arriving at in the US, he had no problem rising up to the top in the more merit-based system here and effecting major, positive change in his field.
So, as is the case with so many other issues, this one is not as cut-and-dry as your comment makes it out to be, and prevents a lot of other good from flourishing as well. There are not equal opportunities for world-benefiting success everywhere.