Our species is not alone in our fascination with the posterior. It is believed that human breasts were even selected to resemble the buttocks. Why? Because our quadrupedal ancestors used to mount their mates from behind.
Lots of different animals still enjoy these interactions today, including humans. It’s not so much “doggie style” as it is universally accepted. When we became upright however, females needed to adapt to this visual conundrum.
Morphology has always been in the best interest of reproduction. Because that’s what life is. Visually absorbing close-ups of women’s posteriors, swaying back and forth, fat jiggling in slow-motion ripples, encompassing the entire screen makes sense. Humans are animals. Life is meaningless.
Ultimately the goal is to facilitate the survival of our species. It is worth noting that prostitution is also indifferent to Homo sapiens.
The cultural structures surrounding our sexual and romantic impulses may seem complicated at times, but just know that we are not alone. It’s taken millions and millions of years for us to become so self-reflective and inane. The evidence lives amongst us, all around.