No, that's not the only good thing they do.
They also pay taxes, contribute to our GNP, do jobs that we don't want to do, provide the labor necessary to keep businesses from relocating or outsourcing, bring experience and skills in the trades occupations that our schools aren't teaching; and buy our lottery tickets.
Reality is that we are dependent upon them now and will become more dependent upon them in the future.
If every single illegal alien went home tomorrow this economy would hum along as it always has. The country is prospering not because of illegals but in spite of them.
So, you are pro-illegal immigration. Thank you for clearing that up.