On other people? Oh hell yeah. They're squishy and awesomely fun to play with. Bouncy or saggy, big or small, boobs are awesome.
But on me? Why would I want something that deforms the front of my shirts, draws uncomfortable sexual attention from males, makes my back ache when I want to run, gets in the way when I want to lift and carry objects, requires it's own separate garment for concealment and support, chafes on seatbelts, makes sleeping on my stomach uncomfortable, makes trampolines look more light a nightmare than fun, etc etc etc...
To actually answer the question? Sex appeal. (at least in many cultures)