I don’t know what you were trying to say in this paragraph, but it makes no sense. Though there is a significant number of unskilled Latina/os residing in the US, this is bad precisely because they aren’t employed in engineering or “high tech” jobs. They are cooks, farm hands, day labor, motel cleaning staff, and drug smugglers. Jobs that Americans supposedly don’t want. Additionally, under the current rules (or lack thereof) nearly HALF of immigrants are living off a government dole — a system designed to support maybe 20% of the population. That’s not stupid, it’s intentional. Purposely overloading the system so it doesn’t work for anyone to justify “fundamental change.”
Perhaps you’re arguing that “unskilled Mexicans” are coming here, learning English, getting free or subsidized education, and qualifying themselves for a STEM career? I’m not sure how that’s foolish, but clearly it’s not happening in significant numbers.
You’re right that there’s no compelling reason to encourage immigration, but your closing paragraph doesn’t support your argument.