Hundreds of millions of people around the world also want to come to the United States. That's why we have immigration laws and quotas, to make immigration an orderly and measured process. If we implemented your idea, we might as well get rid of our current immigration laws because foreigners around the world wouldn't even waste their time filling out the necessary paperwork to come here. They would simply hop on the next plane to the US, and after arriving, they would say that they're planning on staying and want to become a US citizen.
I think we need to totally revamp our immigration, travel, and trade policies to reflect who are our "friends" and who has sided against us in the war on terror. We have El Salvador and Poland sending troops to Iraq to die alongside ours --- but we have an open border with a country like Mexico which turned against us and hasn't lifted a finger to help. We've got Michigan filling up with Muslims who claim they want freedom --- but why aren't they fighting for it with us in Iraq right now --- but instead trying to get their hands on any dollar they can?