Key words: well designed. The current green card/legal immigrant program is not a problem, it is the illegals who are.
People come here to work without any intent of becoming citizens, and not just from Mexico.
I have met people from all over the world working in the oil patch in the US, they are here to gain experience, and will return to their countries and work there, probably for the same corporations they worked for while here.
It is the people who come here illegally who are a problem.
As far as the Federal handling of Katrina, well, most of that bungling was in allowing the press to present the SNAFUs of NOLA as being the Federal Government's fault. Properly handled, those birds of blame would only have been allowed to roost where they belonged. The foul-ups were mostly on the PR end, not so much the logistical one.
The issue of 'guest workers' falls along class lines. Non college educated Americans who compete in service jobs with illegals will never support any 'guest worker' program. It is not in their socioeonomic self interest.