Of course, like anything in photography, context is the key issue. The intention behind using the models, the context the photos will be viewed and the meaning of the photograph are important to consider before rendering the photos as carnal, malicious or abusive.
Has the photographer chosen these young girls specifically to pose and sexualize for an indecent audience, or have they chosen to use the model for their form and aesthetics to create a meaningful photo? Has the child AND their parents given consent?
Having come from a dance background since I was around 2.5 years old, I've grown up with issues of sexualization and exhibition of the human body through aesthetics, costuming and movements. There are always going to be perverse people in the world, they can walk through the streets and eyeball eight year old kids, watch movies, tv shows, use their imagination. Some people are sexually attracted to animals, does that mean we should stop using images to advertise Zoo's or pet shops? I think it's very important to remember there are at least two sides to every story and everything can be done tastefully, meaningfully and memorably.
I don't really know where I stand on this issue.