No one involved cares about the old books. This isn't about the old books. They're still in libraries. They're still classics, and worth preserving and reading. Go check them out!
What's happening here is that the owner of the copyright wants to sell new books to parents. And some of the content is a little off to modern parents, and they think they'll sell more if they modernize it a bit. This has happened before, and it'll happen again.
Basically: it's all about making a buck, and in particular capitalizing on the Matilda film.
Everyone here is thinking "ZOMG Political Correct Censorship Claims Another Victim", but what we actually have is "Han Shot First". Not as fun to yell about I guess.
"Han Shot First" is the artist changing his own work.
That is entirely different. The reason everyone is yelling is they intuitively sense how wrong it is to posthumously edit an artist without permission. There's a moral question here that exists apart from copyright ownership.
But what if it wasn't authorized? What if it was public domain? Would you make the same argument about a modified Shakespeare performance?
> The artist is dead.
That is why I used the word "posthumously".
> This is absolutely being done with the permission of the copyright holder.
That is why I said there was a moral question aside from the purely legal question of copyright.
> What if it was public domain?
I would 100% make the same argument. The problem is changing an author's work without their permission, and failing to indicate that. As others have said, if this were marketed as "The bowdlerized Roald Dahl" in clear print on the cover, it would not disgust me in the same way.
> Would you make the same argument about a modified Shakespeare performance?
It is typically clear in these cases that Shakespeare is being modified.