The thing with trying to make nice looking and more stylish curlier hair is the fact that EA had decided to go with the lowest poly hair possible. If you look at the majority of the hair, shape wise, they are very simple and the details are just painted on. If they were to make truly soft, flowing springy curly hair they would need to make it much higher poly. (and probably use alpha textures to get those individual hair strands).
Hair is some of the highest poly items in any game if it's done right.
And quite honestly, I'm not sure EA could do it justice. Have you really looked at some of the hairs? That one short haired dreadlock one looks like they have caterpillars growing out of their heads!
The other issue people complain about is the lack of swatches for the hairs, the black is blue tinted, the red is over the top, one of the blondes is an ugly greenish platinum or a gold bar. I only use the brown hair for almost all of my personal sims.
