Yeah it'd be good not to look like everybody else. But I still use a rare cloak as I like the look of it (was a white one I liked but i dismantled it by accident a long time ago). I'm sure there are other good rare weapons and armour that would be good to transmog, even uncommons and commmons. That'd be a very very long list of items which would require a lot of work from them. It'd be nice sure, just not sure we'll be seeing it any time soon and if we do they'll probably limit it to exotics and legendaries which would be a bit of a shame.