The publisher is clearly doing this so they can make more money just like any other good capitalist.
There are a lot of calls for this to be "illegal" in the comments. That would be a ludicrous level of government oversight on the publishing process and certainly a violation of the First Amendment in the US.
The owner of the rights to the work is free to change the work in whatever way they want, and they don't have to ask our permission or the government's (thank Christ!). This isn't a case of some sneaky leftist changing the content behind the owner's back. The owner of the content is doing it, actively and knowingly, for bigger profits.
They know a certain demographic doesn't like it, but they've done the math, and know where the best money is.