I am a US citizen and I don't want to live in a country that has a "guest worker force" with reduced rights and no path towards citizenship. I don't want this because I think it's ugly (and societies that engage in too much of this are always ugly), but I also think that it's bad for citizens as well as the people treated this way. A healthy society should not have its employers maintaining a labor force full of employees who can be shipped back overseas whenever the company feels like it: this is a recipe for labor abuse, and such abuse can harm citizens as well as non-citizens. So TL;DR if you're over here working, I want you to have some rights and a path towards citizenship. I don't want a bunch of people slaving away at 2am and being told this is a privilege.

ETA: I am not saying the H1B program is that, just responding to the sentiments up above.