I give credit where it is due; black voters could have put Hillary in the White House with better turnouts in PA, MI, and WI, and they chose not to (especially the men - you know, the “super-predators” that apparently wouldn’t be brought to heel).
Donald Trump’s slightly better showing with blacks and Hispanics is driving much of the enemedia attacks now; they are trying to whip those groups back on the plantation before the mid-terms.
You're also right that the Left is apoplectic that Trump did even marginally better with minority voters in the last election.
Obama-ites are also worried about an emerging consensus amongst black academics that Obama's eight years were worthless, in practical terms, to the lives of most black Americans.
Today on NPR I heard a prominent black professor, Deborah Dickerson, say something shockingly disrespectful of Obama -- it was so bad, I don't think I should repeat it here (lest the Left use it to accuse FR of being racist!).