It's part of the standard "progressive left" stuff - irrational prejudice and discrimination based on the belief that biological grouping (with the groupings defined by them, of course) is identity and should determine social status, legal status, available opportunities and in the USA they've now gone as far as mounting a very prominent campaign bluntly stating that a person's life only matters if they're the "right" "race". All groups are equal, but some are more equal than others. The only part of the "progressive left" that's missing from this particular incident is the part that's most important to them - extreme authoritarianism, with them as the authorities of course. He isn't (not yet, anyway) demanding that everyone obey him in deed, word and thought.
I'm fairly sure that the "progressive left" movement is based on reading Animal Farm and 1984 and taking them as guides to obtaining power rather than as warnings. From Animal Farm they get the idea that biology is identity (based on the trivial biological traits they declare to be of paramount importance), that the biological groupings they decree should determine social status, legal status, etc, and that irrational prejudice and discrimination is "equality". From 1984 they get the other part of the foundation of their ideology - extreme authoritarianism and the importance of corrupting and degrading language as one of the two main ways to suppress dissent (the other, of course, is the power and will to do harm to dissenters). They've merged the two more than Orwell did, since they've taken the biological group identity from Animal Farm (where it was obviously only meant as allegory) and merged it with the authoritarianism of 1984 (where the group identification used was national rather than biological). Other than that merging, their ideology is straight out of those books, the very things those books were opposing and warning people about.
Discrimination is equality. Enforced conformity is diversity. Intolerance is tolerance. Authoritarianism is liberalism. Freedom is oppression. Regression is progression. Doubleplusgood Newspeak, Citizen!
They're scum. I have less contempt for the grotesque bigots who are honest in their opposition to equality, diversity, tolerance and suchlike.
As a footnote, I see they're quoting JK Rowling making that incorrect statement about her own writing. In the books, Hermione is explicitly stated to have very pale skin, with so little melanin in it that a reduction in blood flow in her skin makes her skin white, actually white and not the range of pale pinkish beige that's inaccurately called "white" when referring to human skin colour. You need to have very pale skin indeed for it to go actually white from a reduction in blood near the surface.
My position is this:
If an actor is playing the role of a real person or a pre-established character then they should have at least a reasonably close resemblence to the established appearance while playing that role.
I've no objection to actors using make-up or whatever to change their appearance for a role. That's part of acting. So, for example, if Idris Elba was to play James Bond in a film set before 1962 (i.e. as the original James Bond, the one described in the books) he should be made up to look like the description of James Bond in the books. That would require using makeup to fake much paler skin than Idris Elba has, obviously, and maybe some other changes while they're at it. If he's wearing full-face makeup there's an opportunity in place to subtly adjust his appearance closer to the description in the book. Dye his hair if it isn't the same as described in the book. Wear a wig if that's a better way to get the colour and style right. None of this should be a problem for an actor - pretending to be someone else is their job and they should (and usually do) want to do it as well as possible.
I'm not bothered about it not being done in productions which don't have a suitable budget or enough time. For example, the actor playing the central character in the TV series Blind Spot has to spend up to 7 hours in makeup to play the part. It wouldn't be reasonable to expect that sort of level of makeup in an amateur production or one which has severe constraints on budget and/or time. Lindybeige did a video about it in LARPing a couple of weeks ago ("Who can play an elf? LARP's thorny issue") and his positon was essentially "it's fine as long as you make enough of an effort for other people to be able to know the role you're playing". Mine is the same, in that context.
I think most new roles could be written without specifying many aspects of appearance. If for example, you're making up the role of a fictional doctor for a TV series you're going to need to make up some aspects of their personality...but you won't need to decide on their sex or "race" or height or whatever. You can leave that until after finding an actor you think suits the part and just have the character look like the actor. Job done, lots of money and time saved on makeup. The actor playing the central role in the TV series Blind Spot has to spend up to 7 hours in makeup for the role. That's not something you want to be routine. It's not at all practical. In that case, it is necessary. It's a key part of the character that they're covered head to foot in complex, intricate tattoos.
I am bothered and I do object to the racist hypocrisy that is currently fashionable.