Not that i agree with their views, but the excuse is that all these characters are the athlete archetype and the tan is implied from being outside training daily.
It just exposes the japanese mentality towards skin tones.
It is still racist dude.
Being outside in the sun all day means a 24/7 tan that never goes away through the whole anime series. Athlete sporty, tomboyish, whatever the case is it is still a trope of adding blackness without having to add blackness.
Those character never lose their tans, their skin is never really a serious subject of the plot, they don't face racism, bigotry or whatever a black character would face in a story that is representing the real world.
All Japanese manga are made by Japanese for Japanese, I am not claiming any of those tanned characters need to be black. I am just pointing out the tans are never realistic 99% of the time. Every series has one or two tanned characters. Bleach, Naruto, go a little beyond using the black with white hair trope. It is still a copout. They want those characters to be perceived as black, powerful, cool, sexy, exotic. Whatever the goal is they are using that skin tone for that effect.
Any black kid in the west looking at dark skinned characters in Manga or Anime instantly identify themselves with that character. Urd was my favorite Goddess even though she was just the half sister of Belldandy the main Character.
was Urd tanned 24/7?
Black with White Hair? Always in anime dark skinned characters are always in an in-betweet state as they can go one why or the other. This is done to make blackness more palatable, it has worked wonders. White people get to say Urd is white, she has white hair and a white sister. Black people in the US knows the one drop rule, if part of you is black you are black.
Making dark skin more satisfactory to racists, is not a good reason to create 24/7 dark skinned characters with oh thats a just a tan pass. As a black person I just can't dismiss the use of the skin tone. Most of the time the story and plot does not really call for it. If training outdoors made you that black then the Summer Olympics would only have one shade of skin from all nations.
The point of the thread is Nintendo made a clear choice to give options to the inklings to represent other races where these skin tones did not exist in other Nintendo IPs. This is mostly from the same people who gave us Animal Crossing New Leaf with a Beach Tanning feature for skin choices.
They could have added the same feature in Splatoon if that was the direction they wanted.