My gosh. You know, it would be one thing if the "yellow people" were the ones getting upset at your terminology. Lol But that's not the case, which is really bizarre. *shrugs*
It could be their diets. Asians tend to eat a lot of fish which contains, well, fish oils, which are good for a lot of things. They also eat a bunch of other stuff that I'm not sure (I'm like an Americanized Asian - lol), but many have their reasons for eating what we may think is strange. (Watch the Andrew Zimmern show.) "Turtle leg good for heart." or "Frog heart good for joints" etc.
The "yellow race," as you put it, does have a look unique to no other: flatter facial features, squintier eyes, etc. I guess it just boils down to other people's perspectives of what "young looking" is.
I'm an Asian myself... I have no problem with people calling me yellow. Heck, I don't wear yellow because it blends too much with my skin! Lol *winks*