In a woodwind quintet there is usually a flute, an oboe, a bassoon, a clarinet and a horn. Kind of odd don't you think considering it's a woodwind ensemble.
As for the visual aspect, yes it would change but is that the end of the world?
I find it funny that you used the clarinet as an example for the horns down effect and your right. It's the least dramatic of all instuments. But what about insturments that go from vertical to horizontal and vice versa. Those are pretty dramatic horns down. Maybe not the effect of what a brass instrument does for you but you have to admit it gets the job done. :]