Openness to immigration drives economic success
cityobservatory.org
cityobservatory.org
It's all about money. Don't let any of these feel-good articles make you think differently.
I also find it ironic that the same people that complain that there needs to be an increase in the minimum wage also want to flood the market with cheap labor from overseas, which will reduce American's wages.
Silicon Valley would probably be quite happy with a policy which allowed less overhead for visas without any visa-related job mobility restrictions. They fight for more H-1Bs not because they particularly like the H-1B, but because it's what they have, and it's a lot easier to win (or at least avoid a big loss) over quotas than over the fundamental structure of the immigration system.