Horses are over trained in every discipline in the world. When a horse really enjoys a certain activity, whether that be a slow, low headset or a fast paced higher headset like a jumper, then that discipline is not a waste, no matter how "impractical". Horses are rarely used as actively and practically as they were, with some exceptions. Trail riding is just as much a fun activity as showing is. Just look at how hunters have evolved.
I agree that you must ride in a discipline to judge it. Those who have and then have formed opinions, more power to you. I love what western pleasure has done for my horse, but everyone has different experiences. I do agree that this particular discipline has some issues, but I don't feel like I am in any place to judge it as a whole based on the faults of some riders and trainers. I commend the discipline as a whole for working to correct issues.