I had someone pose that some question when I said I was a lot more accepting of Ricardo Montalban as Khan than I was Benedict Cumberbatch. The point is it's called whitewashing. Not other-ethnicity washing. By allowing someone who is not-white to have a title role, you are opening the floodgates for others to get those big name roles. The right ethnicity actors will be finding themselves getting a lot more work once the floodgates are open. But at the same time, you'll probably never be able to get all the actors you need for a certain ethnicity role. Unless it's you and a bunch of friends, anyways.
As I mentioned, Cumberbatch as Khan was a disservice. It was ignoring Roddenberry's original philosophy. By having someone who was black, or someone who was Latino, in big roles (Uhura and Khan respectively) you were telling non-white people that yes you can get jobs in Hollywood.
It's about representation. When you constantly put blatantly white people into roles that are not-white, you are sending a message. The opposite message to what I said above.
TL;DR- yes, it's better if it's someone not-white but not quite 'full blooded Egyptian'. At least at this stage. It's not perfect by any means. But it's better than having an all-white cast for non-white characters. (Also arguing about how they don't really exist is kind of a cop-out argument)
And yes, the movie isn't that big of one (even with those really recognizable actor names). But they obviously have the budget for them. If they have the budget for those guys they have the budget to get people who aren't white. It's not hard to find black actors. You can find plenty of them for the bad guy roles but suddenly you can't find any for good guy roles? I find that hard to believe.
