Progressive ideology is meant to foster control and power not make sense in a world where capitalism would raise the general standards of society. They can't take over if they don't break it first. therefor raise the minimum wage and bring in cheap illegal labor. There, it's broke now let your betters fix it.
As for immigration legal or not to say that no one was talking about this or paying attention is just towing the MSM line. No one in the media was talking about anyone's immigration positions until they got the message of hatred they wanted to tag on the R's. It's not like those positions weren't out there...just no one payed attention.
We probably wouldn't have near the illegal immigration problem, if the GOP hadn't thrust amnesty on us, in the form of 3.2M illegals. After that, it makes sense why more and more illegals kept coming; they believe it will happen again.