I think the shock is less that the new 007 is going to be a dark complected woman, and more that 007 isn't going to be James Bond. Like, conceptually, 007 is a title, so the tag could have belonged to anyone. But as mentioned, it belonged to one character, James Bond, for 26 movies. I kinda get though that's easier to replace the character completely than to try to change the character that's already established as a womanizer across 3 or 4 decades of films.