The high cost for US students in undergrad is one reason for this. These schools haven't been lagging behind because grad students found a to H1->GC->Citizen. If that path becomes difficult, then these students will just stay in their home countries.
The most significant research happens at the graduate level and beyond. US students are disproportionately under represented at the graduate level. https://www.nytimes.com/2017/11/03/education/edlife/american...
The high cost for US students in undergrad is one reason for this. These schools haven't been lagging behind because grad students found a to H1->GC->Citizen. If that path becomes difficult, then these students will just stay in their home countries.