These days they try not to limit who they cast based on race.
What does that have to do with anything? If Domino doesn't have (abnormally) white skin (not meaning Caucasian just to clarify, in case anyone reading this doesn't know Domino she has skin the color of snow), its not Domino. Its like making Hulk purple. You can do it without changing one thing about the other aspects of the character but it would still instantly make the adaptation bad.
If there is something bad about painting someone of certain ethnicity in white (meaning the color of snow) makeup, then you cast someone where it won't be a problem. If that limits who can play the part, so be it. You wouldn't cast a woman to play Batman or a white guy to play Luke Cage, but that doesn't mean you're "limiting" the casting for those roles. Domino has unnaturally white skin. That's as much of an unchangeable fact as, again, Hulk being Green or (to use a non-superhero example) Spock having pointed ears. If a certain actress can't do it, she shouldn't be cast in the part. Don't use the character unless you're going to put some effort into adapting them.
Then again, in a franchise that has screwed up adapting a whole lot of characters, from Lady Deathstrike to Sabertooth to X-23 and beyond, I'm not shocked that they've completely screwed up with Domino. I like the comic character, but I can't say the same about the movie character that's using the name. But, a single badly adapted side character isn't enough to ruin an X-Men movie (otherwise every single X-Men movie would be unwatchable in some way, although I suppose Wolerinve Origins comes close although its really the writing that ruins it). I want to see the movie because of Deadpool and Cable. The fact that we're not getting a real version of Domino sucks, but unless she suddenly becomes a focus I don't see her bringing down the movie too much.