Right, they are called MAT Pose Files... :)  If you just called them MATs, it's to close to Material + Collection, so it's set up for confusion.  Folks already call too many things "Morphs", for example of things that already get confused.

As far as other file types willy-nilly all over the place, to use your own term, the folders act as "drawers" for a reason.  The core library folders, to me, are by internal type, so clothing goes in figures because it uses the figure structure.

I just feel like if the structure is not going to be followed, why have one at all?  In that case, just move to the DS system, where there is none at all.

.