Sure. The Unix philosophy is generally the way to go (although it doesn't quite save you from being ambushed with unexpected complexity, since modularization usually has to be balanced against efficiency and memorability). I guess the major block there is the complexity involved in mapping an existing complex system onto a few variables. In my experience you would really want to start with the few variables and design around that rather than the reverse.
Ultimately my bet would be on something like GMIC filters or GEGL xml stacks, where you basically have a complete language to code the relationships as text. A GUI model is probably possible but very far from trivial.