For a certain kind of person, using a construction with "the" and a demonym is hopelessly archaic, indicative of some sort of racial discomfort on the part of the speaker. For example, to say, "I am friendly with the Blacks" instead of, "I am friendly with Blacks" is often a point of comedy for some, suggestive that the speaker in actuality has a strained or unfamiliar relationship with that particular ethnic group. As of this question's writing, a Donald Trump, a United States presidential candidate, is widely in the news, and is, to my perception, widely mocked for his continued use of such constructions.
But why should this be so? Consider: "I am friendly with the Amish" and "I am friendly with the Jews". The latter does sound a bit more strange to my ear, but neither sounds that off-key. My question is, is there some sort of rationale or rule at what point a demonym must depart from "the" to not sound socially awkward? Is the strained quality of such constructions, which I can recognize, merely a social recognition—that is, I am recognizing that it is marked only through learned social cues—or is there in fact a deeper logic to this awkwardness?