My own view is that this is a mistake, because it erodes the link between the work and the historical context that produced it.
Naturally, as with any act of censorship, people turn to Bradbury's Fahrenheit 451 as a reference point - a couple of the better posts I have seen are here and here.
What is not always being reported is that Alan Gribben, the Twain scholar behind this new edition, is supposedly doing it in order to encourage US schools to start using Huckleberry Finn again, after a serious rapid decline in take-up of the book due to the presence of the N word; an interesting strategy which is explained in this Daily Telegraph blog.
I think Gribben is wrong, but the debate reminds me of two aspects of Bradbury's F451. One, obviously, is censorship of great literature. But the second is something that Bradbury has said many times: "You don't have to burn books to destroy a culture. Just get people to stop reading them." I like to think that this latter point is what has been motivating Gribben.