I also said why I thought unfairness in this particular case is bad
You said "I find laws that discriminate based on national origin to be unfair, in the sense that they limit good outcomes arbitrarily." Good outcomes for whom? Often a good outcome for one person is a bad outcome for another. What are the reasons you would prefer one person over another?
Society is thankfully not a zero sum game. In many cases, an immigrant having the option to move to a new country is gaining a significant amount of utility, and the citizens of that country do not lose as much as the immigrant gains (they usually even benefit from the immigrant's presence). And in the cases where the immigrant is taking too much, there already laws in place to counteract antisocial behavior such as stealing or fraud. We already have laws to limit bad outcomes, so restrictions on immigration should tend to cause more harm than good by bloc...
As Multiheaded added, "Personal is Political" stuff like gender relations, etc also may belong here.