1. So, here's the thing, actors act. In theory they play people who do things they would not necessarily do. Their job is to make the audience believe they are that person. Is it conceivable that an actor could do that across cultural and racial lines? Yes, it is conceivable.
2. There is a long history of actors playing across racial and cultural lines. Off the top of my head, Mickey Rooney played Japanese, Madonna played a Latina, a goodly number of white folks have played Middle Eastern Biblical folks, Emma Stone played a multi-racial white, Hawaiian, Asian, woman. (There's also things where Pacific Islanders are cast as Asians, and vice versa. Or as Middle Easterners.) 7. And look, in the end, I don't want to make a hard and fast rule, but...um, hi. Let's look at how historically people of color have not even been allowed to play themselves in media. Let's think about that. And say, that sure, someday we might be in a place where everyone is judged by the content of their acting, but we're not there. And, let's face it, the implicit assumption in there is that there was no one of the correct racial and cultural makeup to play that part, which come on. Give me a break.
8. But "Hamilton" you say. Sure, I love "Hamilton". And sure, if you want to cast your entire cast color blindly, go for it. But then, I refer you back to number 3, if you really went all color blind, your cast, especially your main cast, should not be all white. If it is, I question your color blindness.
9. And if you are the person who has been cast cross-culturally and/or cross-racially, the answer isn't, well, we look a lot alike, or it doesn't really matter, or skin color isn't the important part. And that's super extra true if you are saying this as a white actor. Because, come on.