There's certainly some truth in the criticisms based on Poser images being assembled from other people's work -- meshes and poses and textures and all. But then you see a collage. I wouldn't try to define art, and I'm not sure that I know it when I see it, but a part of what makes art is how the artist assembles something which is more than the sum of its parts. Pictorial art is about making choices. Poser gives you a different set of choices.