I strongly disagree that there should be an all inclusive representation of 'race' in The Sims.
Instead, the game should focus on a more complex sims creator tool, adequate enough for the player to create a sim of any appearance.
TS4's CAS is good, but it can be much better. As you mentioned, it should have unique sliders for certain features that are currently missing. Really there should be height sliders.
Skin tones and skin details should be expanded by adding new swatches, or through a complete CAS overhaul. There should be a greater variety of hair styles, including textured hair and more natural colors.
I'm a hybrid of about 50 different 'races'. I can't find a preset of anything that looks like me, because my 'race' doesn't exist in game. I'm not even a 'race' anymore.
What I am is a human being with a blend of different physical features. And in the end that's what everybody's appearance is. A blend of physical features.
It's not Maxis' job to represent every single race in The Sims. It's Maxis' job to give us the right tools so we can create a sim that looks like ourselves, or another person with unique features, or something completely ridiculous that doesn't even exist in the world (Or so we think...).
That's why it's a game. If a tool like that exists, no one has to be disappointed.
