I think this is kindof an important question. "If it's so insignificant, why do you care?".
I don't think it's so hard to understand why some people might be irritated, though. The social attitude that motivates the change to switch away from the term 'master' is not widely held outside of a subset of Americans who are apparently vastly over represented in making these kinds of decisions. It's a bit grating to be saying "consider how others feel" while ignoring how most people feel about it, and making the change made you want anyway.
It's a zeitgeist which results in things like someone complaining that VSCode including a candy cane icon is more offensive than the swastika, and the VSCode repository acceeding this complaint. - I feel if that's where you end up from wanting everyone to feel welcome and included, that you've gotten lost along the way.
Allowing this faux diversity change will only lead to more calls for other faux diversity changes, so the time spent pointing out its vacuousness is well worth it.
Just as security theater isn't real security, diversity theater isn't real diversity. We must stand up and denounce diversity theater and those who profit from it so that we can get focus on diversity efforts that have substance behind them.