Fantasy Hair Room:

You enter hair room and hair splines are automatically placed on pre-defined scalp area which every figure would come equipped with.  The Hair is at a mid length and shooting straight out in all directions, as if no gravity, much like it currently does.

A few logical numerical 1-100 settings (Note:  not different systems different scales different numbers, but all percentage based) named sensibly and you hit a real-time simulation button, and the hair falls based on the settings.  Now, in real time, you can adjust these settings and see, IRT, the effects.

Gravity is it's own setting, And multiple wind systems can also be in place to direct the fall of hair in real time.

When you have something you like, stop the sim.  If you make the hair splines fatter, the texture map acts accordingly by adding more texture/Trans from the source map, which could very easily be a universal vertical map of hair.