I think the difficulty in that is the "all concepts' requirements". The thing is that there is no such thing as a fixed set of requirements, because the game and its content have not been designed in full yet. This project progresses toward a rough goal, but the particulars are very much something we make up as we go along. That's simply the nature of the development. It's more about making the game than working towards a completed game, if that makes any sense to you.
That said, I also think we need a more structured approach to our art and its requirements.
