“Obedience” also known as basic skills are often the only skill set a dog learns and because of the psychological implication carry with them a weight of importance. Non compliance is somehow seen as a severe infraction. If a dog is asked to twirl and does not comply , for some reason the infraction is no big deal. Tricks are seen as icing on the cake, so to speak. But if we mix the skills together then the “drudgery” of “sitting” or “lying down” on cue is included in the playful and more appealing aspect of the “tricks” a dog can perform.