Well, to look at it absolutely intellectually honestly, they aren't saying they want illegal immigration, though they pretty much want to keep illegals who are already here and seem to favor giving refugee status to pretty much anybody who shows up at our souther border.
They, including those who would have given Presidents Carter, Clinton, and Obama any amount they proposed for a physical barrier between us an Mexico, and that includes many of them who argued publicly for such a barrier, are now saying no money for a barrier that the President wants. And now any who want such a barrier 'hate brown people' and are racist.
They are all hopeless hypocrites. You can find any number of them supporting a physical barrier over the years. One of the most glaring is "The Border Security Act. . ." that Senator Schumer himself introduced in 2006 and passed pretty much unanimously by all the Democrats. It authorized funding for a physical barrier.
In the second paragraph: "(Sec. 3) Prohibits the Secretary of Homeland Security (DHS) (Secretary) from processing applications for registered provisional immigrant status (RPI), as established by this Act, until the Secretary has submitted to Congress the notice of commencement of implementation of the Comprehensive Southern Border Security Strategy and the Southern Border Fencing Strategy."
https://www.congress.gov/bill/113th-congress/senate-bill/744