The casting debate is an interesting one. It drives Jamie wild but I can let it go. Who is to say that trade didn't bring Asians and other cultures to Greek shores? And certainly, it'd be historically plausable - it wasn't an isolated white-euro world then but part of a network connecting continents through migration, trade and war, so I'd definitely shrug and let it go after the initital jarring. I also think back then race was looked at a lot differently to now. It's interesting to see how our reactions to race in the film probably are part of this current cultures way of seeing.
However it's probably more about how casting should serve the story, not become the story - we wouldn't debate over it if it was that great, because you'd forget the casting immediately. Jamie, for example, cannot watch anything with Matt Smith in it because he just, for some reason, can't stand him! I'm not that much of a Matt Damon fan, so this film isn't that high on my watch list. Still, I'd be a bit annoyed with Helen as black as she was always described as fair - so yeah, a bit of faitfulness to the original text is a bit better than this obvious and quite banal switcheroo. I mean, why?? - just as I'd think why Anne Hathaway and Matt Damon.
But ultimately, I can't help thinking that it's probably not even about the casting choices but the cultural moment we're living in now, right? First of all there was no diversity in film, now there's too much - like we do need to throw a black female James Bond possiblity in the mix, for goodness sake? We can certainly examine why we care about these details so much - it makes for good conversation and critique.
I can definitely side with those who see Odyssey as myth not a reconstruction of history - it's been translated, adapted and reshaped for thousands of years - as 
I'll choose not to watch it I reckon. It just doesn't interest me. I don't want my view of the Odyssey tarnished by Nolan, tyvm.
RE: The Odyssey - Well, that was unnecessary.