There are hundreds of millions of people who would very much like to come to the United States. They are ready and willing to start working and contributing taxes now. We can pick and chose the skills we need, not invest for 22+ years and hope for the best.
We only need the product you are selling because you use your political power to prevent your competitors, with a superior product, from entering the market.
That's predatory behavior, not altruism.
Westerners in general isn't child-hostile, even if US labor practices are, and many of those immigrants -- including the Hispanic ones -- are Westerners themselves.
What we have going here is attractive enough that we have people lining up out the door. We don't desperately need you to do us a favor and bless society with your children, despite the fact that every parent seems to think we do.
In any event, your logic is flawed. A person can easily be a net contributor over a lifetime without having children. And someone who has children, can easily be a net drain even after attributing some of the costs/contributions of the children (which may well also be negative).
They aren't prevented from coming to the United States by people having children, they are prevented from coming to the United States by US immigration law (either because they are individually undesirable, or because they exceed the hard total or per-country caps in various permitted categories.)
So, relevance here is missing.