I think it would be easier (from the user perspective) to implement a models tab, in a similar way to the materials one. If we make a mistake with a texture, we can upload a new one, so I think it makes sense to be able to do the same with models.
So a tab where we can manage all the meshes in the scene, reupload an individual mesh, add new ones, assign materials to each one, etc., would be ideal, imho.
Also, if that was implemented, then we should also be able to create new materials.
It would be also helpful to be able to duplicate an upload, this way we could have kind of a template to start with or to make variations of similar products.
I know, too much stuff, it's easier to ask than implement, but that was my two cents.