I think the reason for US not implementing any points-based system is that it's simply not that much needed there. US universities are constantly ranked as best

I think the reason for US not implementing any points-based system is that it's simply not that much needed there. US universities are constantly ranked as best in the world (6 of top 10 and 5 of top 5 technical universities are located there according to Times index), their (very skilled) foreign graduates constantly use K-* visas as a step towards a work permit of some sort and almost nobody of them leaves. Add relaxed immigration rules for Canadians and Australians, and last, but not least, the H-1B pool. Of course, folks from the Google's HR will tell you that there's a huge shortage of technical talent out there. Still, given the US education system's power, introducing points-based system might make more harm than good. Denmark, to the best of my knowledge, had points-based system around 3 years ago. I just checked nyidanmark.dk -- it's not there any more. Have no idea why.