Ones that came to the US as students in top engineering programs are cream of the crop and should be welcome. They actively drive innovation and create more jobs here. Grad schools pay them money to attend.
Those that come straight on H1B visas for employmemt purposes from offshore outsourcing companies are cheap labor and should be illegal. No H1B visa should be awarded in engineering field unless the recepient has attended an American university and paid the dues before taking up a job here.