Here is a really interesting series by Ukrainian photographer David Dubnitskiy. In this series, he depicts models in a moment of old-fashioned agrarian work: picking grapes, laundering clothes in a creek, and harvesting wheat. There is nothing modern within the frame. Although created in the 21st Century, they seem to deliberately evoke a pre-Modern, pre-Industrial time.
Although each image is carefully posed and composed, they still feel somewhat spontaneous, even voyeuristic, as if the young women are so focused on the toil of their chores, that they don't notice, or care, that their breasts are bared. In this sense, there's a simple physicality to the work. Anyone who has labored on a farm knows this; when you use your body to work in nature, there is little energy for modesty. Blisters reorient the brain's priorities, and the safe-garding of the body seems like the prissy privilege of the urban upper-class.
In a similar vein, women workers of the field, or indigenous tribes in Africa, South America, and the Pacific Islands regularly worked topless. They had no idea they were being "uncivilized" until European missionaries took it upon themselves to point it out.
But speaking of Europeans, in Art History, there's the tradition of the heroic "woman of the nation." Think of the French paintings like "Liberty Leading the People"(1830) of the woman of Liberty holding up the French Tri-colors in the midst of a raging battle field. She has one breast bared. This symbol of woman of strength and patriotism seems to work in these images by Dubnitskiy. The young women are healthy, hard-working, and the very salt of the "Mother Country." On this level, the images feel not only patriotic, but almost propagandict. It's the same concept the Nazis and Early Soviets used; the message was, "our future is in the pure strength of our past," and symbols used became the idealize young, healthy men and women of an idealized past. The symbol of the USSR was, after all, a hammer and a sickle--just like the sickle held in the right hand of Dubnitskiy's wheat harvester.
On the broadest level, these women at work in the field relate to the ripeness of agriculture--especially in the images of the plump grapes, the golden wheat--wine and bread--the very essence of Western Civilization. But even broader than that, the combination of the harvest and the naked female breast dates back to our earliest human memory. The oldest nude in civilization, after all, is the Fertility Goddess. In this regard, the women themselves in these photographs, and particularly their ripe breasts, become symbolic of the fecundity of land, the very Earth itself.
But regardless of how these images are interpreted and laden with symbolism and interpretation, they also act purely on an aesthetic level: they are beautiful.