Except as a phase in an overall redesign of our legal system of immigration I do not see as compelling rationale for mass deportation other than that suggested by Timothy Snyder:

“Deportations are a spectacle to turn Americans against one another, to make us afraid, and to get us to see pain and camps as normal. They also create busy-work for law enforcement, locating the “criminals” in workplaces across the country, as the crime of the century takes place at the very center of power.”

It is worth noting that Trump has not called for an overhaul of immigraton laws by Congress.