It feels much more disturbing, though, to just silently update the language in the books to be more in line with modern sensibilities. Dahl was a man of his time, and as a general rule his books have good morals and values exhibited in them. They are perfect children's books, not afraid to dip into a little darkness or to poke fun at the adults who run the world, and that's a huge part of why they've been so successful and universally loved.
The mental attitude and sense of self-superiority it must take to feel comfortable taking the knife to something so well loved is really mind-boggling to me. I am very happy that I bought our collection of Dahl's books before this happened.
Of course, once he reaches an age where he's old enough to better understand explanations of racism in media, etc, that's a different story. All cultural history has attitudes that may have changed or that we may even view as repugnant. It's important that people learn about the past and what people were like in the past (or still today).
Maybe this type of thing would go off much better if parents were given a choice, and have the opportunity to confront these things with their children when they think they are ready.
How horrifying. This is where you as a parent are supposed to find opportunity for a lesson on evaluating media. "This is an inappropriate joke but the rest of this movie is so good that I'm letting you watch. Don't make fun of peoples' accents." If he's too young for that lesson, he's too young for the movie.