It's decisions about market fit by executives, not a moral crusade (as we have seen, Hollywood execs aren't really the type for that). Sometimes the whole film is affected, as in Blade Runner, Brazil, Once Upon a Time in America, or Kingdom of Heaven. Those movies were "butchered" (to use the language of the histrionic Forbes article). Yet in Leon (The Professional) the director supposedly intended the titular character to sleep with his underage protege. I'm glad someone overrode the sacred "artist's intent" there, and I wish someone had done the same for George Lucas's ill-advised Star Wars editions.
Here someone probably looks at a report and says, OK here are the movies in our pile with more than 20 slurs in them. Let's try to get that number below 10 so we don't have to add a "the language in this film represents the time in which it was made..." warning, that turns a lot of people off.
These decisions get made to maximize shareholder value, and the original film is not lost (except in the case of Star Wars), it's just one of a dozen variant cuts — you think they show the same exact movie everywhere in the world? Ever been to China? Believe it or not art is flexible and resilient. A film can survive a temporary blip while some VPs try to minimize complaints from sensitive viewers. If you disagree with those viewers that is another issue in my opinion.