The assault charges notwithstanding (I don't really have an answer for that, other than "it was a long time ago", as per other comments), NWA is an interesting case. If you listen to 'Straight out of Compton', one of the defining albums in "gangster rap" as a genre, it paints a picture of LA which is like a dystopian future - where the world is blacks vs whites, people who live on the street vs cops, and where the options are kill or be killed. No matter how rough you had it growing up in the 70s and 80s LA, you would not have had it anything like 'Straight out of Compton" portrays. This kind of imagery in a film would not lead to lingering questions about the morality of the screenwriter or director, but it does for musicians.
In music we seem less able to separate the story from the artist than for other artistic mediums. Is it because many rappers maintain a public persona which is in line with that presented in the albums (even though it's not in line with the way they really are), or is it because music is still generally considered to be primarily about raw entertainment, rather than storytelling? It's interesting.
Yeah, those are all true. It's also not an open and shut case for films either - if a director consistently made films with antisemitic attitudes, questions would probably be asked about that director. Similarly, people have in the past questioned Quentin Tarantino's very frequent use of the word 'nigger' - though I personally think it's a stylistic choice than a racist one.
At the same time, no one is suggesting Matthew Weiner is a mysoginist because of his portrayal of men and women in Mad Men.
There's a similar split in stand up comedy, where if you wear a costume your "character" can say vile things and people laugh in the knowledge that you don't actually believe them, but if a stand up comedian's "character" looks no different from the actual stand up would off-stage, then people often mistake these things for the person's actual views.
In music we seem less able to separate the story from the artist than for other artistic mediums. Is it because many rappers maintain a public persona which is in line with that presented in the albums (even though it's not in line with the way they really are), or is it because music is still generally considered to be primarily about raw entertainment, rather than storytelling? It's interesting.