My cousin married an illegal mexican. He is THE hardest working person in our entire family (works 60+ hour weeks slaughtering chickens , talk about a shit job). He even spent 10k of his earnings for a lawyer to get legal citizenship and the lawyer basically fucked him over, kept the money, and they couldn't fight it because he was illegal. He's been deported twice and has still come back. He pays taxes like everyone else. He is an honest, hard working person that actually contributes to society and to a country that he feels is truly the greatest in the world. He doesn't leech off our healthcare system, he doesn't lower the property value of the houses around where he lives, and he actually wants to become a citizen. What's wrong with that?
Fact is Mexicans work hard, harder than almost any other nationality, and generally believe they'll have better lives in America. Sometimes gaining legal citizenship is too time consuming or not cost effective. Not saying I'm an advocate, actually quite the opposite, but if an illegal citizen contributes to society as much as a legal one, I really don't have a problem.