I completely agree that it would be great! The way Rockstar made meshes, however, makes it really hard to switch outfits onto different bodies without some mesh editing or other ways of setting up the file. At least that's what I've found while trying to get a handle on the body/clothing meshes in game.
In other words, it's harder than it seems. Hopefully some super smart modeler will take on the challenge. As the tools progress, so will the capabilities to alter these kinds of things.