Of course they are consumers - if we seal the borders, my prediction would be another recession (or worst).
Well if we threw out every illegal, and sent the saved tax dollars back to the taxpayer, that would likely offset any loss.
And, our Culture is far more important than 4.3% growth v 2.1% growth.
Don't worry about that, because you're wrong. After the emancipation proclamation, 10% of this country was slaves. Guess what? No recession. Somehow we survived without importing slave/cheap labor. And we will this time. Contrary to what you would like to have us believe, this country was not made on cheap illegal labor.
But what an interesting recession it would be. Help wanted signs everywhere and rising wages. Congress would not need to take any measures like extending unemployment benefits and welfare costs would fall as people were induced into the workforce. Most Americans would experience an improved standard of living. It would be the kind of recession that was hard on the rich but good for the middle class and the poor. I've never seen one of those before and I think I might like it.