Any kind of limiting number of particular group of media files (while not doing it with another) would be imposing a censorship. However, other kinds of limits are mostly negotiable. For example, it is not the same if we have a photo of poor quality of some village from Papua New Guinea and a photo of poor quality of yet another penis.
At the other side, as Jon mentioned in one and I inside of another thread, working on software solution in accordance to Internet Content Rating Association [1] principles and methods should be fine: We should allow to our users to choose which category of images is offensive to them.
This is a perfectly flexible method, as it can deal with all kinds of taboos. We are dealing now just with "Abrahamic taboos" (sex and Muhammad images), but we didn't touch any of taboos of many small cultures. By allowing users and editors to say "I don't want to see images of that sacral place" we would give to all cultures equal chance to protect their taboos. At the other side, Commons would be able to keep its own policies related to free content, image quality etc.
[1] - http://en.wikipedia.org/wiki/Internet_Content_Rating_Association