Male biology undergrad students first meet the word "cleavage" in embryology class. Later on when time permits for some girl ogling (usually after the embryo exam!), the word takes a new and more interesting meaning.
I read with much mirth the news article on Democratic presidentiable Hillary Clinton. I think Ms Clinton should be nonplussed and even congratulated. At least she had no qualms about expressing some aspect of her sexuality (that obviously had caught Bill's eye) despite the position of power that she aims to get.
I don't think revealing some cleavage "objectifies" women. In Darwinian sexual selection sexes really objectify each other. After all why should female birds put a big fuss about how colourful or big a male's feathers or wattle!
It is the female that does the selection. And we taxonomists know that the females really choose their mates on the basis of the attributes (the secondary sexual characteristics) of males.
The Washington Post writer who wrote a 746 word article on Hillary's cleavage is a woman. And a woman has an interesting secondary sexual characteristic which a man like me always takes notice. This woman should be congratulated. At least she knows about what a woman has that could attract a man.
That's how evolution goes. The females get to select. Now I have to tell that to the social gender constructivists. Darwin's theory is more parsimonious.