Used to be AQHA horses were shown in halter and performance, and there were individuals that were raced, shown in halter and performance. Now the horses are specialized for each discipline.
Regardless of how the horse is ridden, shown or bred, it should have good conformation. There are bloodlines that naturally have a level head carriage and are slow legged.
We have halter horses that are shown in halter and shown under saddle. Halter horses that win are not obese. They are fit and conditioned. Fitting and conditioning a halter horse is hard work. It requires exercising the horse (many trainers pony their halter horses with golf carts) and lots of elbow grease grooming. It takes about an hour to throughly groom a horse including vacuuming it.
Showing a horse well in a halter class is an art, and it takes practice and skill to do it well. For example, you have about 6 seconds to get your horse set up and posed for the judge. First impressions count.
Granted there is always room for improvement in all aspects of the horse industry, but I get tired when people slam those who don't want to ride but want to enjoy their horse by showing it in halter classes. There is nothing wrong with that. Not everyone wants to ride and there is no law that says every horse has to be ridden.
This our son with his 4 year old APHA mare:
A new blog about showing & conformation:
http://wabbitears.blogspot.com/2007_08_01_archive.html
PS. At an Open All Breed Show last month, one of our daughters showed her Impressive / Jackie Bee Bred halter mare in Showmanship (won it), Reg. Mares 4 & under (2nd), Walk/Trot Western Pleasure (won it), Adult Western Pleasure (2nd), Horsemanship (2nd), Cloverleaf Barrels (3rd), Straight Away or Figure 8 Barrels (2nd) and Poles (2nd) and she won the High Point All Around Buckle. So you see Halter horses can get the job done, if the owner chooses to do more than show at halter with it.