Given the fact that most illegal immigrants are a natural constituency of the Democratic Party and actually radical political movements, why would anyone want to bring millions of these people into our nation?
Finally, why do proponents of illegal immigration or amnesty ignore the FACT that no deportations are necessary? Just enforce fines on employers and the labor market would dry up and force them back home.
In an ideal libertarian world, I would have no problem with open borders, but we aren't there yet.
These new immigrants are an invading force whose legalization would dramatically change the political landscape, and not in favor of libertarianism.