So you think that some child who had no choice to come here and has went to Kindergarten and middle school and high school should just be tossed out because YOU want it?
Man, I can feel the love of Jesus coming from you! /s
It's because that's the law—and not just in this country, but in every other country. It's a good law. There's no birthright citizenship anywhere in the world, because it's unworkable. If my daddy steals a car and gives it to me, that doesn't give me a right to it, even if I didn't know it was stolen, and even if I've gotten used to it and take wonderful care of it. It's stolen property. I may be innocent, but that doesn't mean I can keep it. I don't own it.
You call it "tossed out," as if there's something wrong with these folks' home country. (Doesn't Jesus love the folks in that country too?) Sometimes your daddy gets transferred. Sometimes it's to another country. Look at it this way: If they have a house and sell it, they'll be rich folks just about anywhere south of the border.
The reason sentimentality is only for liberals is that it leads to bad consequences—like illegal alien gangs, out-of-work American kids, vote fraud, and Press 2 for English. As the lawyers say, "Hard cases make bad law." It's not worth the destruction of America just to keep poor little Dora the Explorer in second grade.