Pick a Marvel character. Any one of them. The chances are incredibly small that their race plays little part in their part of the story. (obvious exceptions include Black Panther).
Now, let's make Wolverine Japanese, Jubilee Scottish, Tony Stark an African Pygmy, Doctor Strange Indian, and Warmachine a mid-west hillbilly.
Yes. It matters. Staying as close to the source material is better.
The comics get rewritten and reinvented, yes, but some things remain consistent. One of the least changed things is a character's race. Because in comics, how a character looks is important for identifying them.
For Domino, it matters within her backstory. Because she was a test-tube baby that was born via surrogate. Who her parents were is important to her own story.
It's focused on because it wasn't an accident. It was an intentional choice. The film industry focused on it because they wanted to make a political statement, so yes, people are right to respond to it.
If they wanted to make a NEW character, or declare to people that this is specifically NOT the same character, that would have been much better.
Don't take something and change it if you can just as easily make something new. Especially if changing the other thing would have irritated others and taken something away from them.
I know I personally don't care about a character's labels, because it's how the character acts and what they do that matters to me. So I'm able to relate to a character regardless of their labels.
To me, it's a bit insulting that the media seems bent on changing characters and adding minority groups to things to "give them representation" and "give them someone to look up to". I thought the point was that those labels shouldn't matter. But once a character has a label, they should stay that way. It becomes part of the character, no matter how small or seemingly insignificant.