3D Hair items were made within the hair forger that allowed you to create segments of objects that acted upon physics, which you would be able to set a texture type for the hair, how long or wide each strand was, and so forth. This hair forger is one of the older parts of the games code that isn't used much or is relatively outdated and somewhat hard to work with.


3D Objects on the other hand, like my Feline Ears, works as a static object and is binded to the bodypart known as the head, so it will display on the head, and move as the head would, but will not have any 3D physics.


3D hairs are right to be assumed as uncommonly made due to the fact on how hard using such an old tool is, not necessarily because 3D hairs are NOT wanted. It's not impossible, it's just VERY very difficult.