To get the best and the brightest from other lands to further enrich the US society which is much better primed to be a fully heterogeneous one than most anywhere else on the planet, and that’s just from an economic advancement point of view, not a moralistic one.

For clarity, I’m making no argument for merit based entrance. You don’t know who the best and brightest are when they’re crossing the border, and you don’t know who’s descendants are going to make the world better for you and yours.