A lot of authors re-edit their own work in new editions to remove things they've changed their minds about or realized were inappropriate. Creativity is a process dependent on editing to begin with, as creators revise and refine their ideas as best they can before publication, and there are always mistakes we miss or better ideas that occur to use after the fact, so most creators welcome the chance to make a few more tweaks. I've done it myself in the collections of my Analog Hub stories (a couple of which had uncorrected mistakes in the original editions), and in my novel Arachne's Crime, whose first half is an expanded, revised retelling of my debut Analog novelette and replaces it in the continuity of my main universe.
So generally, I feel that the revised version should count as the authoritative edition, in the same way that a final draft supersedes a rough draft. But I suppose I can understand that sometimes a reader may prefer the original version. David Gerrold went back and revised his novel Yesterday's Children by adding a dozen new chapters that completely reversed its original, bleaker ending in favor of a more conventionally upbeat one, by revealing that a character who'd been misguided and paranoid in the original had actually been right all along. But I prefer the original ending, which feels more honest, or at least fits better with my sensibilities. Yet the advantage of the way Gerrold wrote it is that he just extended the story without changing a single word of the original text, so the revised edition of the book is actually both versions in one -- you get the original if you stop with Chapter 28, and the revised version (later renamed Starhunt) if you read all the way to the end. Which is a classic illustration of Orson Welles's maxim that "If you want a happy ending, it depends, of course, on where you stop your story," only in reverse of what Welles probably meant (that every happy ending is undone eventually).
