Because of this, there was a huge reaction by fans, both positive and negative. People who supported the casting said that that would help increase representation and diversity in a major series, where the default was assumed to be white. Critics however said that broke continuity, referencing the 1999 drawing by JKR, where Hermione was drawn as white, and the "Hermione's white face was sticking out from behind a white tree" in Prisoner of Azkaban, as well as Emma Watson's casting for the films.
There was overreaction by both sides, people saying that if you disagreed with black!Hermione you were racist, and some others saying that black!Hermione is "disgusting".
There has already been much discussion, with the main thread on the Harry Potter Reddit garnering as of now 945 comments. https://www.reddit.com/r/harrypotter/comments/3xovk9/jk_rowling_on_black_hermione/
(can someone help with this?)