I have no problem with reforming the immigration system. However, I do know the motivation behind why some people would love to have the immigration policy be as Switzerland and it's not our nation's safety either.
Plenty of people will always want the right thing for the wrong reason. Here's the thing, though. It's one thing to hate people of another race and want to go around exterminating them. It's another thing to speak with honesty about the limits of assimilation when two groups both look extremely different from each other and have radically different cultural backgrounds. Simply calling for "more tolerance" as the liberals do isn't going to cut it. Groups with radically different cultural and physical characteristics are naturally going to go off into their own spaces, and accomodating this reality might sadly involve restricting immigration flow from nations with histories so distant from ours.
Now, if it's JUST that the groups look different, but have the same culture and dedications, perhaps they can overlook visible differences. African-Americans, for example, have never known anything but Anglo-American culture--yet even their full integration has been and continues to be problematic. (Incidently, some people have speculated that this might be due to our extreme relaxing of immigration laws prior to their full integration; they never got the chance to "catch up" to whites socially and economically before they became but one among many minority groups competing for attention and "equality." In fact, I'm told that the immigration of African Muslims to the U.S. has drawn some a few [not many, thankfully, but a "few" converts is still a few too many, IMHO] African-American males into the Mohammedan faith.)
Mexicans, by comparison, are more recent arrivals, more in touch with their homeland, and more prone to want to be loyal to Mexico and/or turn us into the United States of Amexica.
And what if we have a successful integration system that erases any major cultural differences between the ethnic groups? Could ethnic nationalism break out again? Possibly so, if a) the different groups for some reason suddenly have more contact with their cousins (i.e., through immigration), and b) there is a serious economic downturn. This may just be a risk that heavily multiracial countries take, and therefore I believe that heavily multiracial state should be handled with care.
Of course we should always treat everyone with respect. But if it's clear that someone doesn't want to be a part of the United States (not just an economic beneficiary), he should be denied citizenship.