Questions regarding Immigration Policy

Here are a few questions and statements from a debate with a friend that I thought would be interesting to share, whether as questions, ammunition for other debates, or just fuel for thought:

I'll just put out a few questions then because I'm genuinely curious what you think: what does it matter if children are living here and their parents didn't go through the official regulatory processes?

If a family has been here for decades and settled down, has kids, the parents have jobs... what is the point of deporting them? Why go to the trouble and expense? Is that justice, or is it going out of your way to flex legal muscles and prove a point?

So a different question: what is the point of forcing immigrants through lengthy, expensive, convoluted immigration processes anyway? 


Is it to stop terrorists from getting in? Because I guarantee you that most of our border and airport security workers are underpaid quasi-legals incapable of correctly identifying terrorists (is anyone able to identify a terrorist based on their face and a pat down?) and besides that, I'm sure the handful of terrorists are going to find other ways to get in.  
We have 5,500 miles of border with Canada, 2,000 miles with Mexico, 95,000 miles of coastline, and the air above our heads. Reality is that neither a wall nor a plexiglass bubble the size of Trump's ego is going to keep out terrorists (although saying that never got anyone a vote.)

So is it to keep out "bad people"? First generation immigrants, illegal immigrants included, have lower crime rates than native born Americans. They're people determined to travel and work hard to get to a better life for them and their children. I'd say "bring on the immigrants", but it looks like they don't want to come to America like they used to anyway.