I know someone from an Eastern European country who did her PhD here and was told if she went back to see her family after finishing she would not be allowed back into the US for 6-9 months minimum. She has spoken English since she was about 3 years old. Why should we punish her for doing her research (and contributing to American science) here?
Going a bit off topic here, but as a FYI ...
My understanding (from personal experience) is that once you open an application, you are not[1] allowed to leave the country until it's finalised. The length of time for the process (whatever form it takes) to run its course is highly variable, and it isn't at all unusual for it to exceed statutory or reasonableness standards (think 15 years for a green card and you'll get the picture). However, one can put through a parole request (yes, the form really does say PAROLE OF AN ALIEN or some such nonsense in all caps and in bold at the very top). If granted, you are allowed to leave for a short duration. IIRC, it's a "once-only for family emergencies" type of thing.
As for fast-tracking those coming to the US for doctoral research, tbat's an excellent idea. In the interim, however, I'd happily settle for not seeing high school honour students detained or deported for immigration violations^H^H^H^H^H^H paperwork errors. The system is rife with inequities, and the climate so political, that I see little hope for any sane merit-based policy to prevail.
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1. Actually, you're free to leave at any time, but doing so typically terminates your application, leaving with you no practical hope of obtaining legal residency in the future.