in my experience, from reading comments and feedback here and elsewhere (CG Society, app specific forums, etc.), most people don't have as good an eye for bad anatomy as bad lighting and bad materials.

how you arrive at good lighting and good materials is your own choice.  GC is a tool for letting the computer handle color correction universally in a mathematically precise way. like any automated tool, it's only as useful to you as your workflow allows.  no one's suggesting GC to people who aren't having material or lighting problems.  but  when i see yellow bloom and muddy shadows, and i see it in render after render, i suggest using it (among other techniques).

just to clarify, i think GC is a tick box in Poser Pro and Poser Pro 2010 render settings (i don't have either, but i've seen screen shots).  i don't have Poser 8 or PP 2010 either, but i know IDL is part of the render settings.  they seem more complex.  

VSS is not the sample skin shader template distributed with it (a very common confusion).  VSS is the Versatile Shader System, which is for making it easier to control all the materials in your scene.  if you wanted, for instance, to implement a toon shader on everything in your scene, while retaining your color, bump and displacement settings, VSS would be very useful. the sample skin shader template for VSS implements a skin shader on your figures with the goal of realistic skin.  that skin shader has GC in it, and a lot of other features.  but VSS doesn't actually have anything to do with GC.  it would be great if VSS had a slick interface and was simpler to create templates with, but it's still in alpha or beta or whatever.  it's also one of the many tools bagginsbill works on in  his spare time.