That may be true, but (a) the damage is done, (b) we have 11-12,000,000 Illegal Aliens here now, to deal with and (c) we must prevent that from happening again.
Again, it's only bad in your mind because you are a bigot. This country has been absorbing immigrants for centuries...
Here's what we do to "Fix" it.
12 million who are already here should be granted an amnesty, if they self-identify, with a case-by-case review. This worked just fine when Reagan did it 30 years ago.
The way to prevent future problems is to have a guest worker program that will allow cheap seasonal labor. Actually, when we had an open border, these folks came up for the harvest season, and went home when it was over.
What caused the "Crisis" is that 1) NAFTA devastated Mexican Agriculture by forcing Mexican farmers out of their own market and 2) Increased border security on our side meant that instead of going home at the end of harvest season, you might as well stay instead of keep having to navigate your way past.
But the only "Crisis" we have is white bigots living in mortal fear their daughters might date a Mexican.