Because for some reason society has equated breasts with a sign of emphasized femininity and for a lot of women, bigger breasts validate their sexuality and womanhood.
"Some people can thrive and bloom living life in a living room, that's perfect for some people of one hundred and five. But I at least gotta try, when I think of all the sights that I gotta see, all the places I gotta play, all the things that I gotta be at"