the united states is a country founded by migrants and has continued to have the most amount of migrants anywhere in the world, several times over the next most. the united states naturalizes roughly 700,000 people each year.
contrast this with say, china, which has something like 1,000 foreigners who have obtained chinese citizenship? total? in a country of over a billion? the result of course is a more cohesive and racist country (if you're not han, you're shit) but also there is a flight of intellectual capital as you can't be dual citizen with china and another country so people leave. whereas in the US? people come here from all over the world.
i do believe we should have a fairly open immigration policy. it's fine if we want to control our borders, but people should be able to come in here legally without much issue
in regards to the ban, i think when a majority of people -- as the polls indicated -- supported a "muslim immigration ban" before the election, they were mainly thinking of refugees coming over here and us having to support them for the rest of their lives. that's what people supported banning. the rejection of visas is not what i think many people had in mind. so i can certainly see why people are upset about it, and i think polls will indicate people are more against this order than for it... but probably only slightly.