Is this okay?

PW reported that author Myla Goldberg, substantially rewrote her novel, Wickett’s Remedy when it was released in paperback:

"Because of the unusual format of Wickett’s Remedy (side notes appear
in the margins of many pages), it had to be re-typeset for the paperback, which
gave Goldberg the rare opportunity to substantially rewrite parts of the novel."

I've heard of correcting errors on new editions, etc but not rewriting parts of the book. Then I started to wonder, is that right? What if more authors started to rewrite parts of their book? I mean I'm sure plenty of authors would, but something about it seems wrong. According to PW, Goldberg revised and developed certain scenes and threads of the novel. The article goes on to say:

"But Wilson and Goldberg denied the revisions as a tactic to sell more
books; in an interview with VelocityWeekly.com, she said, “I feel terrible for
hardcover readers. They’re your most loyal readers, and here I am penalizing
them. The last thing I want to do is make hardcover readers feel like suckers.
It’s not a gimmick to sell more books!”