Gentlemen,
There eventually will be a Mission Editor that will allow users to create missions with AI traffic, as is the case in SS 2008.
The Free Roam environments are usually not heavily populated because not all players want to deal with it.
AI is a principal frame-rate killer. The inter-frame processing load is very high because dynamics must run for all AI ships in the near view, as well as the path and conflict resolution algorithms. Too much AI can make it impossible for some users to initialize that mission, or cause a QV abort during the mission.
As more experience is gained, and some program optimization is done, you will see more AI in missions and, perhaps, in some free roam environments.
Regards,
Marty