Let me clarify what I mean by "clothing editor", as in the design and actual creation of a clothing item done from scratch and or tools used to create said clothing items. Just changing around textures and UV mapping them to a mesh isn't hard and would take all of about 30mins to add to the game, which could again lead to copyright problems. The actual process of making clothing meshes is what I had meant being hard to add. This would also be tons of work.
What I had originally thought of that could technically work, is making "Pieces" of a clothing item, like for instance, For a "shirt" there would be like:
Shoulders/Neck: Straps, V Neck, Plunge, Off the shoulder
Sleeves: Puffy, Short, Long, Cuffed, No sleeves
Etc, this could work and would be what I actually mean by a clothing "Editor", but this results in needing tons of different meshes for each piece and I think is currently out of the scope of the Dev teams capability. This idea could be expanded into different clothing "types" too, like for instance there could be a "shirt type", "jacket type", "skirt type" and lots of different options in each clothing type. But this idea is extremely far fetched and I don't see it ever being done. It would also sort of fit the theme of "editors" in 3DX as the world editor is just a bunch of pieces that you put together to make whatever it is you're making.