There's an unholy alliance between the leftists, who never saw a criminal illegal alien they didn't like, and the capitalists, who want cheap farm labor. As you say, very little honest discussion goes on.
I agree that the fight against illegal immigration must avoid racism or unjust discrimination at all costs, because the media will predictably use that to demonize the proponents of immigration control. But immigration is clearly out of control and desperately needs to be overhauled and reformed. It's ludicrous that illegals cannot be expelled from the country without huge court costs, and in fact usually cannot be expelled at all, even if they commit felonies. It's also ridiculous that illegals should enjoy all the benefits of citizenship without assuming any of the responsibilities.
The left is hopeless, but we need to work on the forces in the GOP that support illegal or unlimited immigration for economic purposes. In the long run it's self-defeating.
Economic concerns are important, but I look at the national security concerns as more important - if you create the conditions that lead to increased illegal immigration, you make it even easier for somebody to slip through the cracks undetected, who aren't there to make a few bucks to send back to their family.
I think a good policy would be to deport all illegal aliens except for those who have not committed any other crimes and who have close family living here legally. They will be given the possibility of amnesty. Also, since Mexico has been not only the chief exporter of illegal aliens but has also apparently ENCOURAGED illegal emigration to the U.S., we should put an indefinite suspension on all immigration from Mexico--except for family members of those already living here illegally--send Mexico a bill for the public services (at both state & local level) their illegals have cost us, and refuse to lift the suspension until they pay that bill in full.