I don't know about St Joseph, but there have been depictions of Mary which used to be considered holy enough for the churches, but got thrown out in the 19th century. In the south of France, ancient statues of the Virgin Mary in childbirth were destroyed, and those of her breastfeeding were hidden away.
Personally, I don't like nudity in art, especially religious art. But there is a long tradition of it in very celebrated religious places. Maybe it helps to look at images as always being symbolic.
If they were, they've been brought out again. The Vatican Museum displays a breastfeeding Madonna dell'Umilta by Francescuccio Ghissi, and the Lateran Pinacoteca features a Madonna del Latte by Giovanni di Pietro.