I would like to see a feature that would allow you to select a face of a prim that already has a texture on it that you want to apply, and then allows you to 'remember' that texture, so you can apply it to other faces of other prims. Access to this information would be limited to those textures already in either the LL-provided 'Library, or in your own inventory, or embedded in the selected primset with full permissions enabled. For textures you have appropriate permissions on, it would allow you a way to 'copy and paste' a texture from one prim face to one or more others. The reason for this feature is to save the endless searching back and forth through inventory when applying a texture change.
It should be restricted so it could NOT allow you to store and apply a texture that you don't already have, or which is not already embedded in the selected primset, with full permissions. In other words, if you couldn't look it up manually in your Inventory or in the object's contents and copy the UUID, this wouldn't work either. While I would prefer a solution that actually allow you to copy and paste the UUID for use in scripting, any method that allows you to store and apply the texture would be OK.
Of course, there would also have to be a feature that checks permissions on the texture in question, and would only allow this if the UUID led to a texture in your inventory or in the Library with full permissions enabled. This would prevent someone from swiping a copy of a texture that they didn't have the rights to.
Coupled with this should be an ability to selectively apply a texture to all faces in a selected group of objects, or specificly to those faces that already have another speciific texture. You should be able to apply it to faces that have textures that you don't own copies, of, but it should warn you if you do.
For example, I should be able to click on a face that is already textured with the LL Library texture 'Brazillian Rosewood", tell the editor "Remember texture", then should be able to select several prims and apply that texture to all faces, or click on an exposed face with the 'default plywood' texture showing, and apply 'Brazillian Rosewood' only to those faces in the selected prims which have the 'default plywood' texture.
One strong use of this would be the ability for a builder to create (and save in inventory) a 'texture pallette', consisting of a stack of prims that have the textures for this specific build. They could then apply textures rapidly by selecting from this 'pallette' of prims, and then applying the stored texture as required.