I will point out a few things some of which i think are missing in the discussion above. (I did resist posting for last two days but i give up, i just disagree a lot to remain silent, but only this one time

).
- Debate between education vs. skill becomes irrelevant for an employment based system. Both education and experience are proxies for skills and capabilities and an employer is in the best position to determine how much of each is required to do the job. With all the criteria related to university/grades that are listed above you are trying to create a central HR department that will recruit without a job description (or a broad job description of STEM).
- Employment based is a market system, takes care of demand and supply in labor market. Points based (or education based) is more of a planned system and will sooner or later fall out of sync with actual skills that are needed. So today a STEM bill gives Greencards to all people in these areas. In few years if more finance professionals/doctors/lawyers or other professionals not covered in these categories are required the slow moving legislative process will result in market distortions.
It is very hard to win against the market, a good case study is LTCM.
- Overall Employment based system in my opinion does a good job. It is flexible and automatically fills the gaps that exist at different times. It provided doctors in US when they were in shortage and provided Computer/IT professionals when they were needed.
- A country may have good universities in one field and labor shortage in another. The best thing would be to have foreign students come and study in the first field and go back and attract trained foreign workers in the second field into the country (import computer scientists with foreign degrees, export degrees in philosphy or the other way around).
- Overall a simple employment bassed system with fewer categories and constraints is the best option. The current three categories are sufficient (probably more than required). Comparing or prioritizing between two PERMs seems a very arbitrary thing to me. The problem with current system is not in structure, it is again the planned numbers that have been allocated. The numbers need to be increased to reflect the demand in the labor market. If there is manipulation or fraud it must be prevented but i do not beleive it would be more than 5-10% of the entire PERMs filed. That won't change the current backlog materially. Objective should be to ensure all GCs are processed with in a reasonable timeframe of 1 year. The country caps and overall quotas are very outdated. HR3012 would have fixed (and could still fix) the country cap issue and would have made the increasing of the quotas more likely with entire EB community suffering equally (and fairly).
- Creating more categories or coming up with artificial education restrictions will result in unfilled jobs and make the system even more complex and costlier. The tax code has lots of rules but can still be (and is) manipulated. It actually becomes harder to detect manipulation. US law firms overseen by US agencies control the immigration process. They increase scrutiny in H1 and PERM processes and audit cases whenever they smell any manipulation. To put the blame on applicants or even hiring companies is not entirely fair.
Other (minor) technical issues
- US and other global companies hire for their US operations from foreign campuses they view at par with the best US universities. Two people in the same training program at a bank will get their GCs in different times.
- What about people who obtain undergrad degrees from US universities. How do they compare with people with foreign undergrads but US masters. Might be a lower number in past but with increasing wealth in India and China this will be a significant block standing in the queue soon. Should they tell people with US masters that they have 4 years of "great" education vs. 2 years for people with foreign masters. What if they also do masters here should they have another category for people with two degrees in US vs. one.
- Foreign doctors filing for Green cards will still have the old fate and so will finance professionals even if they were educated here.
- How do you compare a person in field X from university A with a CGPA of P with a person in field Y from University B with a CGPA of Q. The answer is in general the immigration process does not need to. The decision is best left to the hiring firms.
My simple point is the more lines you will draw the more divisions you will get. Keep it simple and work towards making it better for everyone.
PS: abcx13, i know your opinion about economists but a basic course in micro and macro economics will help you in understanding the other sides of the argument. (At least i think it helped me).