With regard to the toes as sexual objects:
Some would say that yes, if your toes are a turn-on to someone else, you should cover them for the sake of modesty--yours and the other person's. They also shouldn't stare at your toes.
With regard to breasts as sexual organs vs. nourishment: it's a cultural thing, and if you deny that in modern Western, particularly American, culture the female mammary glands of humans aren't considered very sexual--as a source of visual stimulation and as a focus of physical stimulation--then you've got your head in the sand.
Should it be that way? I don't think so. No more so that toes, like someone said. But it is. At least many of us here have made the first step: recognizing that there's a problem.
Now that would be interesting: 12 step recovery from twisted Western/American body image and sexual values.
I can see that it makes sense to avoid breasts from a "It'll get the site banned in some peoples' workplaces" point of view. Some programs they use match up certain physical shapes of images and block the site or red-flag the user accordingly, to help block porn sites. And breasts are one of those shapes.
Maybe only using saggy natural boobs would do the trick.