I'm normally very sensitive to this kind of thing, but this feels like the wrong approach to me. It's the same fallacy of "strong female characters" being almost entirely "women that are strong/kick ass." It's supposed to be STRONG CHARACTERS, FEMALE. I get that in our modern era there's a huge problem with how minorities are perceived and used in media. But I think that lies more in those characters being flat, two-dimensional "bad guys" that aren't interesting.
The argument should be that brown-skinned characters should be better characters, not that they shouldn't be evil. I think it's regressive to say "audiences should know that when they see a brown skinned character, they're a good guy." No. We should have fleshed out characters of all skin colors, and have people be evil because of their ideas and actions, not simply skin color.
Evil characters are some of our favorite characters in media. Oftentimes a story is only as good as its villain, because a good villain is a reflection of the worst in all of us, and that's what makes them fascinating. Look at the Joker, which is in interesting character and a compelling contrast to Batman. If the Joker was black, would that be bad? No, we'd have a badass black villain character that is really interesting.
In short I think making all brown-skinned characters "good" is really selling it short. It's the same kind of backhanded "helpful" patriarchy type thing where women can't be villains. Fuck that. Dredd was awesome and it had a fantastic female lead villain.
I'd really rather not fix the problem of people being put into one box by saying, "let's put them in this other box instead."
But yes, obviously, if you're thinking, "we need an evil character, how do we visually represent that? i know, let's make him have dark skin" then you should fuck off. And the "color swap to dark skin for evil version" is just stupid and yeah, should stop.