Actually,
I'm pretty sure Tamaki is half-french (so having recessive traits there isn't
entirely strange) Also, it could just be that in the early days that was used as a cost effective means to not have to freehand as much (most animation was done by hand at a certain time, after all... though they could very well still be lazy. It could've also been a strange wish fulfilment; after all, media doesn't
have to always be 100% accurate and hair and eye colors aren't the weirdest things with anime, especially your other examples)
Anyway on the actual topic, yes there should be minorities represented and should be in the limelight. The only caveat I have is when they are seen as a main character instead of taken positively (well, at least thankfully some people do accept it a positive) there's always a group that complies the character down to their basic traits and calls them "just a stereotype" and thus not a good representation. (though, anyone can really be made a stereotype if you just look at them that way)
Though, my biggest problem is the world isn't just black and white, as it seems like some try to force it to be. (and I don't mean color term wise, though that might work, too...) It's never as easy as just using a minority as a character because it can quickly become a heated mess (usually against you, as the developer) even if you get them right. If you're not from that race/culture, even if you took plenty of time to research (if it's necessary) there's still a high chance for people to claim that your "appropriating" or trying to misrepresent them (sadly on tumblr people sometimes even do this if the creators of the media
are of the race/culture being represented; I've seen it... Though tumblr really isn't the best example; I've found people are generally jerks there...)
There's never a 100% perfect representation, anyway; everyone is going to be different so there's no way in placing in a racially/culturally repetitive character everyone of that group is going to be covered. Nor should a minority character be placed in just to have one (for the sake of "being more deserve") Yes, occasionally this can work, but most of the time the minority character just comes off as flat and you can tell they were just thrown in there, or you can tell they were quickly changed if they weren't a minority character before.
Though another thing is as multiculturally diverse the world is, we (as humans) tend to stick to what's familiar; it's why the adage "write what you know" is so well known. I remember (back when I was still using tumblr) there was a blog called PoC (the mods would take questions on writing character of color) and whenever there was a general "how do I write [insert racial type here]?" non-specific question, I'd always think (without looking through the answer first) "as a human, duh." (though, of course some cultures do need research before writing a character from them just in case) It's strange how we seem to have this disconnect of "Oh, I'm not from this race, I don't even know where to start to look for information..." (I've personally found specific web searches and public libraries are extremely usefully for this.)
... Sorry, I didn't really mean to rant (I'm not even sure if all of that is on topic...)