Basically, in my ideal system, you'd have a scale of consistent "views" of any antagonist: one trivially simple but basically correct, then one or more refinements that translate into more completeness -- and more complexity -- with each iteration.
I'm in the process of making this kind of system for Exalted.
4e does a great job on the "simple" view for antagonists, while 3.x did a great job on the "super-detailed" view. What I'd like are tools to start simple, then refine into complexity on demand.
I want scalable complexity: a very simple base system, but with the option to add on more complex and detailed sub-systems if I want.
A sliding scale of complexity, moving in either direction as desired, based upon a basic framework design principle is exactly what I meant by, "'In media res' constructive flexibility" , and to some degree, ""modulated-construct design,"
I personally think that type of design ideal should more or less be an naturally and commonly incorporated design principle.
i.e. simplified rules, with a game that didn't involve that much number-crunching and instead was imagination heavy.
And I know that I'm employing basically technical design terminology, but I very much agree with this ideal generally speaking when it comes to fantasy games, fantasy literature, and/or myth. The first duty of a design principle in such circumstances is to as unobtrusively as possible stimulate and delimit the imagination, rather than over-burden and over-limit the technical and functional components of the overall design. In other words technical details and mechanical components should operate in the background as nearly frictionlessly and invisibly as possible given the particular subject-matter content these components are meant to address.
Or put another way, the guts of a ship are not meant to be visible to all, and they shouldn't be so complex and worrisome that everyone sailing her need be mechanical or technical experts, or attending to or constantly maintaining her vitals. The ship should be made to service the crew more-so than the crew to service the ship. If all hands have to be at the engine room at all times, you got a mighty unweatherly and impractical ship. But if a ship can all but run herself then she is a joy to sail and the crew can be about far more important matters.
Designers should design so that whatever they produce is as self-servicing and easy to maintain as possible.