I definitely noticed and made jokes about the whole black ranger being a Black person thing, but I had never noticed the Asian = yellow one!
The simplest reason is that the American version of Power Rangers (which is, any scene where you see the American actors’ faces) was written for as little money as they could possibly put into it, and thus the quality of the writers was low enough such that things like this wouldn’t have been caught. That or one of the writers was intentionally racist, that could have very well been it. Another easy explanation is that the colors suited the actors best – just imagine the black actor in the pink suit.
Since that all of the suited up action sequences were filmed a long long time ago in Japan, it could very well have been possible for the writers to not create that color and race association. But they didn’t have a lot of leeway. Consider the colors: yellow and pink, blue black and red. Yellow and pink are girly colors nowadays, so those go with the girls. Red is the leader’s color as it’s one of humanity’s strongest and most powerful colors (that’s what you get when it’s the same color as our blood). So you have two characters, a nerdy guy and a generic black guy, and two colors, blue and black. The color blue has had the connotations of peace/science/medical (police officers often wear blue), but beyond that, it would simply look out of place having the black person in a blue suit and a white guy in the black suit, when the other option looks much more visually appealing.
The one thing I love most about the old Power Rangers (other than Rita) is how much it reminds me of the politically correct 90s, the cast of characters is over-the-top diverse, diverse for diversity’s sake only. Just like the characters in Captain Planet.
I have officially thought way too much about this :)