On one hand, a small (minuscule) part of me wants to play devil's advocate and say 'hey, maybe they honestly couldn't find a person of said race that could act'. But there's just no way, and somehow the choice of actors they did end up choosing leads me to believe it was a combination of utter laziness, simple marketing and 'this hunk will make us more money'. But y'know, when I went to see Star Wars, the Gods of Egypt trailer played and holy fucking shit it looks so ridiculously bad and disgustingly predictable (I am so sick of Gerard Butler by now that I just want him to go away). I don't have to see the movie to know every single action scene, every fucking speech (really? Still milking that '300' speech, huh? Got DAYUM), every predictable, done-one-thousand-times-before CGI monster... It's just all around abysmal. Same for the others mentioned; they're shit made by people with dollar signs oozing out of every pore. So the shit choices in casting, the idea that they more than likely didn't even for one second think 'damn, maybe we should get the right races to portray these people', is not even a stretch; the stretch would be that they put any kind of considering into it. Dollars to doughnuts that thought didn't even come close to entering the equation in any serious fashion or even at all.
In the grand scheme of things it's not like this is some huge issue that's hurting tons of people (there are obviously a lot more serious concerns where racism is prominent), but it's just the fact that...it does eventually hurt someone; I don't have any doubts that there are plenty of good actors of the respective races that could've brought something to the film to at least make it not quite as shitty (though in the end, I'm honestly not too worked up over these specific films because they're horrible and would probably do more harm than good to the actors, but it's the trend that's bad). There is just no way that the people behind the films are that ignorant. There is a near certainty that they're that big of dirty assholes and are just that greedy. There are so many of these films now that it's ridiculous, and nearly every one is just so horrible.
I don't know what it is Hollywood is on about now, but the Egyptian culture, stories and mythology is being bludgeoned to death in the past couple years.