I agree. Engineering and computer science programs are overrun by foreign grad students. I think a few more of us locals should get those slots.
While I agree with you in principle, the last time I looked the enrollment rates for Americans in the technical graduate programs was way below where it needs to be to fill up the grad schools. The foreign grad students fill in the gap and many if not most stick around and work in the aerospace and computer industries.
That is not all bad.
If our immigration policies favored college grads that would be a good thing. I worked with Vietnamese PHDs for many, many years. The ones I worked with helped us win the cold war and many were brilliant mathematicians and analysts.