I'm no Robert Plant fan, but I'd be very surprised if he had anything against blacks and their musical tradition he has plundered for his wealth!!! Seriously, Zep had an overt share of blues riff stealing on their first two albums, but you could always hear the adoration they held for that music too. Plant is a thoughtful man, even intelectually aloof, like Petty, when accused of using the word nigger in a song, he could probably say: "I ain't no racist, I don't even drive!"
Back to the album. Terr, what did you expect after his outing with Ms Krauss? The new album is recorded in Nashville and sounds like it. Looking at Plant's solo output, with a few exceptions, he has become more and more esoteric over time. I think he's sincere in carving his own path even though the Led Zep crowd is yearning for him to do something else. His career choice reminds me a bit of what Clapton did after Cream, disengaging from being a guitar hero in a power trio and becoming a singer/songwriter (not that he's excellent at either!) playing a fluid, if less than daring blues lead guitar (he is excellent at that, he uses the same words everybody ion that field uses, but has his own langugage).
I gave the Plant album a first listen today, it's not immediately accessible, but then very few of his solo work is (he left that part of the market to Kingdom Come). Have to give it a few more spins, but it seems to be a logical follow-up to his work with Krauss (and that album was far from being immediately accessible too).