Family watched it last night, we were bored and there wasn't anything else that we hadn't already seen. Anyway, I agree with your assessment. I think it only got all of that press and a over the top Tomato-meter simply because it was a "black" film.
For white movie critics, being less than totally enthused about Black Panther would have been a guaranteed career ender.
Expect BP to sweep the Oscars. Nobody would dare vote for anything else.