Already a great and powerful advantage to using something like this: constancy! Having art that is consistent to itself can be a huge deal if you are a designer and you worry about such things (er, *ahem*)... from a play-perspective, it just provides lubrication to lucubration's luculence (an even louder *ahem*).
Seriously though, if consistency is important to you and you'd rather have your portraits support that, using these kinds of generators is a definite plus. Thanks Ben. You are always hitting up the best spots on the FRUA design beast!