The current skirt model isn't any good, Basically almost everyone knows that when you wear a skirt (not prim works) your butt, saddle and such will grow insanely, forcing you to edit your shape, thing that helps a bit but not totally.
Also its impossible to move the skirt up/down, forcing makers to work with alpha but than you get bad results anyway.
I've been digging source code, xml files and such, and well the big limit for a non linden is the "Linden Binary Mesh File", currently Lindens have posted how to "read" the file, but it would need some work on a 3d program exporter and what not.
Even tho I guess Lindens have them exporters, which don't publish on the open source project.
In conclusion the idea is to first of all fix the 3d model and than add more morphs. All that shouldn't need any special viewer source code edit (well adding the morphs on edit window, that's about it I think).
I doubt Lindens will ever bother with that, even if they should really improve the whole AV meshes, morphs and attachments behavior while moving, to keep up with 3d gfx progress.
So I would like to know if anyone else is interested and wants to work on it. And if Lindens could please post an exporter for them binary mesh file.