1) Miley didn't really get dragged for cultural appropriation - if she did, it played second fiddle to her antics. What black people were irritated with was more the media doing things like saying "LEarn how to twerk, like Miley Cyrus!" as if she, a white woman, invented twerking at the VMAs in 2013
2) Iggy Azalea was dragged for her false southern "blaccent", despite being from Australia. But primarily, she was dragged for being untalented. She became a joke in the black community and the living embodiment of white mediocrity being able to easily outsell/outperform black people in their own craft with her "undistinguishable/ordering chinese food" rap, and that 'freestyle' with Sway

It's ALWAYS been the case in the black community that we will accept white artists making black music if it comes from a place of authenticity, and unlike mainstream America, we will not tolerate white mediocrity. If you're going to be a rapper, you better be able to spit (freestyle being one of the cornerstones of being seen as "legit") & and if you're going to sing our music, you better be able to SING.
3) Robin Thicke was accepted by the black community for his music

He became a mess and a joke following BL with that horrible, cringeworthy Paula era (and just came off as completely unlikable, which was not how you want to rebound after an era heavily criticized for promoting rape

), but yeah, there wasn't really any backlash against him from his earlier days getting airplay and videos played on R&B stations (Lost Without U was big back in the day), nor during the time BL was smashing.
4) Justin didn't get much backlash until recently, and even that was the result of his terrible responses to a bit of small criticism on twitter (which he could have ignored, or responded to better).
Bruno hasn't faced backlash because he is talented and authentic in the music he makes, isn't acting like/isn't being celebrated for 'creating' something which existed before he did it, and so far hasn't been condescending like to criticism from black people about his influences. And also, lets not act like Teena Marie didn't exist, or Lisa Stansfield, not to mention David Bowie who had plenty of soul influenced music
and even performed on Soul Train, etc. Amy Winehouse, like others have mentioned, didn't suffer backlash, and I'm sure Adele would be welcome by black audiences if she chose to come to our awards shows.
And by the way, it's not like Miley Cyrus or Iggy Azalea are exactly critic/GP darlings in ANY demographic, so...
