Jimmy-
The goal of our articles is to be informative, not offensive. It turns out that in most cases (penis, for example) the ways of presenting the content that are offensive are also lacking in terms of informativeness. A photo "in the style of" pornography takes away from our mission of informativeness, while a photo "in the style of" a medical text comports with that mission.
It's simply not true that a photo of a penis or vagina is not informative. Ironically, it is particularly informative in families where the parents would likely consider it offensive. It helps people to actually identify sexual organs and to understand the wide range in their looks and sizes (many people are anxious to find out whether they are "normal"). Every sex education book that is worth its name contains pictures of genitalia.
I would also like to point out that there is near consensus for inclusion of links, and a slim majority for inclusion of photos (where the minority typically argues that not they, but mysterious "other people" might be offended).
Regards,
Erik