This. All of this. I love representation. I love the fact that Hollywood is taking more steps to assure that people like me, as well as others, are given more prominent roles in the media. But for a character like Damian, who is WAY more mixed than just "50% this and 50% that", you're gonna have a REALLY hard time finding someone who both fits that description and is a talented enough actor to pull off the role (no lie, playing a convincing Damian is probably the ultimate challenge for ANY child actor). So sometimes you will have to settle for someone who may not fit the ethnic description but does fit the physical one.
Where was the mass fandom outcry when Storm had TWO live action actresses who weren't Kenyan (added bonus. They're both half white)? Barely anywhere, right? Because both actresses still looked the part (hell nobody even minded that Alexandra Shipp played Aaliyah...well...they did but not because of her race). How about the half-Mexican Jessica Alba playing the white Susan Storm? Or Elizabeth Olsen playing the Eastern European Scarlet Witch (she even got the accent)? Or when they cast a black dude from South Carolina instead of a Native African to play Black Panther (and as a black guy, I can tell you: Yes. There is a difference between being African American and being African)? Fandoms really like to cherry-pick when not being as authentic as possible is okay.