Is the ERD useful for Game Dev?

I think ER diagrams are very handy tools for designing data requirements for a game. I don't see them given away or even talked about (in this context) on the web, and I'm not sure why.

Does anyone else use them? I think if they are stripped of attributes, and simply specify entities and relationships, they can be useful for general design, and perhaps are even re-usable? I have a theory that they form an excellent domain specific language useful for specifying game mechanics. Attributes can be added to a generic ERD, which add behaviour to the model, unique to the game being designed... hmmm.

This is a quick little design I put together to hold the required data for a Master of Orion (4x) style game.