In the show ring, hunters are judged on pace, jumping style, manners and soundness. But an additional criterion is movement, especially in tough competition. The judge wants to see a horse that appears to flow around the course in long, even strides. Movement becomes even more important in hunter under saddle classes. Regardless of how attractive or well mannered a horse is, if it doesn't move well, it isn't going to nab a high ribbon.
Good movement is important in a hunter for three reasons.
First, a real hunter on a foxhunt will cover many miles. The horse needs to conserve energy in order to cover all that ground without being exhausted. Excess knee action and a short, choppy gait not only wear down the horse, but also the poor rider who must keep posting, posting, posting to each beat of the trot. Second, a good moving horse, in general, is a sound horse. There is less wear and tear on the joints and tendons.