For some artists, lack of variety in the model may truly be a problem, but for most, I think they are more limited by themselves than by the mesh. Look at the work of traditional artists, and you often find that their people always look the same. They carry an ideal in their heads, and even though they paint with oils on canvas and are not limited by anything but their imaginations, they often paint the same type over and over. Edward Burne-Jones, for example, always painted slender girls with big, dark eyes - supposedly images of his wife, Georgie. Rubens preferred fleshier women, to the point that his name has become an adjective. People complain that all the Vicky characters look alike...but then they keep buying the same types, over and over. I know I'm guilty, too. A pretty or handsome character is a lot more likely to get my dollars. And often start a piece telling myself I want this character to look different...but end up moving the dials so that Mike or Vicky ends up looking closer to my personal ideal. It's hard to leave them ugly when it's so easy to fix it. ;-)