One of the basic premises of anti-immigrant policies is that you can somehow influence the ratio of "useful" vs "not-useful" immigrants. Apart from the idea of sorting people into useful and useless being inhumane, it also seems to be counterproductive. It looks like every kind of screening of immigrants will deter the more desirable ones, as far as that determination is possible on their arrival at all.
Another insidious equivalence of equating immigration policy geared towards unskilled, illegal immigrants with immigration policy in general. Let the downvotes begin.
It's why Asian-Americans went from being part of the Republican base to overwhelmingly voting Democratic.