The only thing that differs inhabitants of a country from those who immigrated is the luck of being born in the right country. Thus, the only reason to deport illegal immigrants is their place of birth, which would make it discriminating.
Illegal immigration is a crime. A person who is convicted of it can be punished in more effective ways besides deportation, since deportees often immediately return. Since illegal immigration is often driven by economics, it would make more sense for the punishment to be garnishing their wages.
Since you said "all" therefore only one instance is required to counter your premise. Initially all refugees appear illegal since often documentation is lacking. Also some arrive because our nation and our taxes have funded weapons and war in their home country forcing them to flee for safety.
Many immigrants complain that they did not want to leave their countries. They would love to have stayed in their homes. Indeed they love their homes but it has become too unpredictable to live and raise children due to war. The smart and wealthiest leave the earliest. Anyone would do the same. Who wouldn't!? It's quite hypocritical just to declare they should all be deported.
So it depends on one's sense of compassion. If one is not compassionate one will "defend their country" and their comfortable status quo.
If one is compassionate one will realize that the smartest thing in the long run is for all human beings to acknowledge responsibility for the planet as a whole.