I just don't see the purpose of having these defined origin "truths", what does it accomplish for us? If it accomplishes the goal you are after what are the negative consequences of having achieved that?

Again I think the only limits (as opposed to general guidelines, like the Era and Technology, or general world map) we should be saddling our project with should arise naturally from specifically design things that are in our world. (ie the Plot maps define a specific area and so indicates and influences things getting created around it)