@Kaoru:
Expecting Nami to be a white red head is a natural wish, whitewashing or "racewashing" a character is bad
I highly doubt Japanese author Eiichiro Oda first conceived Nami with the idea of her race being "white". If we were to apply real world social constructs such as race to the One Piece world, being Japanese would be the first choice for Nami considering the country of origin where she was created and the language she speaks in the original comic.
And before you rebut with the list of countries Oda chose for the crew if they existed in the real world, we have no idea what Oda was thinking at the time he received that SBS question. We can infer that he probably didn't want to answer the question with a simple "they're all from Japan" response. He probably wanted a more interesting answer and he probably wanted all the characters to come from different countries so that they would be diverse in terms of location.
So Oda, in what can be assumed was not a lot of time, chose places based on superficial aspects (looks, personalities, hobbies) of the Straw Hat Pirates.
The obvious ones:
Franky drinks cola and wears Hawaiian shirts? America.
Chopper is a reindeer? Canada.
Zoro a.k.a. Mr. Bushido? Japan. There had to be at least ONE Japanese rep.
Sanji has French-named attacks and likes to cook? France.
Brook likes music? Austria. This pick feels like Oda did some light research, but it's the least obvious out of the pack.
The least obvious ones:
Usopp? This is unfortunate, but it's all but confirmed that Oda chose Africa (not any countries, just the entire continent) for Usopp based on features that are stereotypically applied to black people such as curly, unkempt hair and big lips.
Nami? Sweden is an odd choice that seems mainly based on her looks than anything connected to her hobbies or personality. Maybe Sweden has a big meteorologist community.
Robin? Russia is not the first country that comes to mind when I think of Robin. Unless it's a slick Russian spy jab.
Luffy? Brazil? This is tough. But if I had to stretch (heh) for reasons, maybe it's because Luffy's fighting style is similar to capoeira, or because Oda's favorite sport (soccer) is popular in Brazil, or possibly that Brazil has the largest Japanese population outside of Japan.
Everything except for Brook feel like picks that were made off-the-cuff, were made without much thought, or the reasons are too obscure to be obvious to normal readers.
Addressing my own biases:
I would love for all of the Straw Hats to resemble how Oda drew them on the page as closely as possible. This applies to skin color for most of the crew, more specifically, the characters with certain hair colors like Zoro, Nami, Sanji and Franky. This doesn't mean I think only white/pale skin characters should play these characters, but if the show decides to keep these hair colors and cast darker-skinned actors/actresses in these roles, then they would have to convince the audience that what they're seeing isn't glorified cosplay. As an adaptation, I'm fully well aware of the limitations that comes with bringing these characters to life and making it look natural.
Not a cosplay, but an actual, realistic group of characters that fit into the world that was created in the show. When I say "realistic", I don't mean real world "realistic". I mean "realistic fantasy". The perfect balance of realism mixed with fantastical elements.
This means features that are exaggerated in the comic (hair, noses, mouths, ears, etc.) will be more subdued or completely removed in the live action show.
Racewashing I think is racist too, and no, I dont agree all fishman should be black like the previous poster said, it sends kind of the wrong message, Fishman are fishman, and people should draw paralels with racism and discriminations from the things (injustices) that happen to them for being different, not the color of their skin
Racewashing as a major problem within the entertainment industry does not exist. Whitewashing has been, and still is, a prevailing issue because "white" is treated as the default when it came to casting in 99% of mainstream forms of entertainment.
Yes, there are cases in adaptations of white characters being changed to non-white, and non-white characters being changed to another non-white group. It's a drop in the bucket compared to the history of whitewashing.