None of the standard concerns regarding crime, welfare uptake, or failure to assimilate (as exaggerated as these are in general) can plausibly apply to this group; instead, these potential immigrants bring much needed talent in science, engineering, and finance. Why are we discouraging such immigration?
Having spent more than five years with my doctoral students at MIT, after their PhDs being funded by the US Government, and finally getting some H1Bs, the reason is simple, it is in my opinion the unions. They have allegedly lobbied so strongly in favor of limiting the visas so that they allegedly can ultimately try and unionize technical labor.
If you want to kill the United States there is just one thing you can do that will be certain, unionize the entrepreneur! What moron would ever do that? In my opinion and based upon my experience the unions would and are allegedly doing so via their malignant limitations of H1B visas. Walk the halls of DC and you hear this talk all the time. Listen to the chuckles of the union bosses and you may be able to hear it as well. In a perverse way, in my opinion the unions and their alleged attacks on H1B Visas are performing acts more malignant to the survival of our country than any enemy one could ever think of. We educate Chinese and then send them back to China where they produce. They create value there at the costs here! Why, because in my view the unions want control.
This will just continue to get worse in my opinion as we see the current Administration progress.