I believe the dominance of Egyptian Continuity and Permanence is multi-faceted.
First, Egyptian painters had a very different way of representing life than what we do today. I'd suggest that this difference is directly related to the purpose of the works of art and monuments. Egyptians were more concerned with completeness, continuity and permanence than they were concerned with beauty. The culture was focused on preparing royalty for the afterlife with the Gods. As mankind was able to move away from the hunting and gathering age to a more agricultural civilization, people learned a trade, skill (or an art) which was handed down and taught generation to generation. It was the artists' responsibility to preserve everything as clearly and permanently as possible. So they did not sketch nature as it appeared to them from any fortuitous angle which would conceal much of the human form. Thus, the "artists" created the images, symbols and hieroglyphs as they were instructed to from a young age, according to a strict set of rules or canons. The better the likeness of the mummified king the better likelihood of immortality. Thus, sculptors were required to create these monuments as indestructible as possible in stone.
Society didn't seem to want anything different or unfamiliar, and artists' were not asked to be original. On the contrary, they were probably considered the best artist who could make statues most like the admired monuments of the past. Society was content and even happy with the way things were. So it happened that in the course of 3000 years or more Egyptian art changed very little.
Secondly, the consistency of canons were a result of society with this happy existence and a good quality of life. They had very fertile land along their lower lands of the Nile, and plentiful hunting lands of the north. Yet men still lived a fairly short life span so they primarily remember a youthful and energetic existence, all preparing and leading them to a happy afterlife. Remember, that this was the first major culture to adopt agriculture over hunting and gathering and thus freeing up time for people to pursue other disciplines and pleasures. These luxuries lead them to believe they were a superior race even capable of immortality. Yet to reach the afterlife, mankind would have to make the soul worthy to face the Judgement Hall where the Court of Osiris had the final determination of their eternal afterlife. Eternal life was reserved exclusively for those who behaved well during life on earth by abiding by rules, laws, canons and standards of the Egyptian life after death process.
Lastly, these virtues of continuity and permanence would reflect and maintain their cultural superiority. Mankind was learning the importance of recording history. Thus, it was critical to tell their story with pictorials and hieroglyphics to demonstrate their superior knowledge of the earth, life, the afterlife, the sun, the moon, the stars, and the Gods. Massive undertakings would build unification of all the remote tribes, for one king and kingdom. These consistent representations of monuments such as the pyramids and sphinx became the symbols of the superiority and strength which lead to superior wealth and more power. Obviously, the Egyptians were successful in creating a "cultural identity" or "logo" that is still recognizable today through coninuity and permanence.