Re racist language, when I first started teaching TKAM, way back in the 60's, 'negro' was a neutral word, on a par with 'Caucasian', and that was how Harper Lee used it. The slang n-word was offensive even then and only used to delineate the racist climate in the region where the book was set.
In the 80's, we had our first complaint about 'negro', in a different context, not in an English lesson, from a black girl accusing an Indian teacher of being racist for using it. In the 90's, I did once have a black girl who refused to read a book because it was racist. She pointed to a word on the first page. 'It says 'black'. That's racist!' It was Comfort Herself, set in South Africa, specifically put on the syllabus to cover the 'multi-cultural' requirement of the National Curriculum. Fortunately, the rest of the class, v diverse, were able to disabuse her.
My view is that it's best not to labour the point. Language changes and, yes, there are words which we would not use now, but focus on the message. After all, TKAM is v much an anti-racist novel.
Besides, that's not why Gove removed the texts. It's because the authors didn't have British passports and he had a bee in his bonnet about national identity, the English tradition, etc etc. rather than the literary quality or relevance of the work.
And so we have An Inspector Calls, a mediocre play by any measure, and not a patch on The Crucible, by one of the C20 greatest playwrights, Arthur Miller, born in the USA.
I agree with pp about the impact on A level choices. So many have been put off by the idea that it's just going to be Jekyll and Hyde Mk 2.