Agreed. People here are mostly thinking "brilliant computer scientist" or "will cure cancer," but many universities have degree programs that are revenue generators, requiring full tuition payments from students and attracting many foreign nationals, which may not be held to the same standards as other programs. These programs serve plenty of students from China and Saudi Arabia whose parents are making an investment in getting an American option for the their child or the family. This is a very rational decision, but I don't think that it serves US interests to give an automatic green card to a kid from (pardon my apparent condescension) Directional State U because his parents paid enough to get him to scrape through a master's in geology or CS.
I'm at a big state U, mildly insulated from the pressures to develop a program at which anyone can succeed, but I have a lot of academic friends who have encountered significant pressure from administrations to keep pass rates high in revenue-generating STEM programs (many of them masters' programs). Attaching a green card to the diploma is a boon to these programs and some non-US students: all the incentives are there to just keep taking that full tuition and graduating students without working them too hard. Win-win, and it cuts down on the end-of-semester "I have to leave the country if I fail!" conversations, which I've had several times and are always unpleasant. These micro-level problems could lead to a flooding of the market with people whose educations just aren't that great.
Coming from a family of immigrants, I'm all for making green card processes more efficient. Knowing America's education system, attaching a green card to diplomas of STEM graduates is pay-to-play and that's not cool.