Support multiple texture variations for a single model file
Morrowind NIF-files have the texture(s) path(s) specified in the nif file. This means that if you want to have texture variations for the same model, for example by having a shirt available in different colors and patterns, you need a copy of the same model for each texture variation you want. This is both annoying and waseful. An example of an annoying situation right now could be if you update the model of an object which has, say, ten different texture variations. Since you would in that case have ten different copies of the same model, you would have to update all ten of them instead of only updating one single file.
To be able to define a texture path in the CS (to override the one specified in the nif) or in another way would be much more efficient and practical. Many other games do this.