It does amuse me, how often the people who complain about these changes, declare it's not about race...and yet the point they are bitching about, is the race of the character.
Playing devil's advocate, you can easily turn that around and say "if it's not about race, why change it?"
Anyway, TBH, for me, it's usually a case by case basis, though I'm usually on the side of "OMG, who cares?" when it comes to it. It's gender-flipping that tends to irritate me more, though there are cases where it's a non-issue.
I remember...I think it was a discussion on 1.0 of the escapist, about the trend back then for changing up the traditional lineup of classic heroes. FemThor, Korean Hulk, etc. And somebody commented about someone else being Spiderman, and that "Peter Parker" is spiderman, nobody else. And I remember commenting "ok fine, but there's nothing inherently white about Peter's character. I mean, his key traits are 1. Kid from Queens. 2. Awkward and nerdy. 3. Compelled by guilt to fight crime. That's it really. And pretty much every other aspect of him, is just Regular Human, and could be filled by anybody. Which means you could have a black Peter, and it still be fine."
That's a reasonable point, but I have two words - Miles Morales.
If people want to play the diversity game (which is a game you can't really win, but whatever), it struck me that a better way to play it was to create new characters rather than change old characters and say "look, see how woke we are!" I mean, if we're playing the game, what's the better outcome - blackwashing Peter, or creating Miles? Speaking personally, the latter. Because while you're right in that Peter's ethnicity has never really been a factor, I prefer Miles in that he's his own character, who has in-universe rationale for existing, and is a fun, enjoyable character. Granted, my experience with him is limited to Into the Spider-Verse, but hey, you can't really go wrong with that movie.
Kamala Khan is a similar example. I don't know if the relationship between her and Captain Marvel can be said to be equivalent to Peter and Miles, but whatever, I've read some of her comics. She's fun. She's a character built from the ground up, and as far as I can tell, was received positively.
Oh, remember when they announced Zendaya Coleman as MJ, and people kept posting comparisons pics of the two?
When looking for differences between the two, I was less struck being Zendaya being (marginally) darker skinned than MJ, and more that MJ's bodyweight seemed to be about 10% breasts.
I know there were comparisons, but breast size? Really?
Anyway, TBH, MJ in the MCU is a good example of what I'm talking about. To me, she isn't Mary-Jones Watson, she's Michelle Jones. A separate character. Yes, it's a clear reference to MJ from the comics and whatnot, but even casting appearance aside, Michelle's personality is completely different. Which, to me, works. Michelle's a fun character in fun movies (well, one being a lot more fun than the other granted). So everybody wins.