This has come up before. The use of the term "migrants" for these lawbreakers seems to come from the Mexico City newspaper. If it's an accurate translation, it's all we need to know about the open border concepts.
Migrants bring their culture and values, or disdain of such values. Immigrants accept the laws and values of the country they enter. "Illegal immigrants" can't very well accept our values and laws, since they broke the law to get here.
And the cheap labor? It's a double edge sword. Low wages to get a lawn mowed or dishes washed or whatever is good for people who won't do it for themselves, I guess. But, social problems and extra government expenses, downward pressure on wages of citizens just trying to make ends meet, impacted neighborhoods, money being sent out of the country, these are not plusses.
I'm not a bigot or racist, but I do believe that people have to be part of an established culture, family, religion, community etc. to thrive. This isn't happening.