The game has no complexity at all. Don't confuse complexity with a flood of material required to build something.
In fact if I see how simple the missions are done or the BGS by design (there is no real economie to start with) I wonder if FD avoided game complextiy at all cost. It's a pitty because good games require a certain complexity (= life) to give a good experience. Doesnt mean the user have to see it. That can all be hiddin in a good BGS. It just have to work and make fun.
Idk, I've been playing 21 months. The BGS still has new surprises. It's a fairly deep mechanic. About as complex as combat. If Frontier wanted a strong (non-combat) leg to expand upon, the BGS would be a good place to start.
If they added a more dynamic and changeable economy, colonization, station enhancement and building, all without the need for nose-leading CGs, then the game would be in a much better place.
Actually owning created player bases and being able to pledge to a minor faction, with special perks, would be a huge step forward as well.