I am aware of all of this. But again, your examples are anecdotal: Of course there are going to be “full inbounds and empty outbounds” in reality. But in the greater scheme of things, traffic balances out. In AirlineSim, due to the limitations of the simulation (like the 3 day booking window), an imbalance between inbound and outbound would be the equivalent of a real-world route that people only ever fly in one direction. Not something that’s all that common, I think 
That said, the “older brother” of yesterday’s change is on the roadmap for a reason: Return flight bookings. It should be able to capture many if not all of the scenarios you mentioned…it’s just no minor engineering challenge and will require more tooling for players (because you can’t just book two weeks worth of flights into the system and hope for the best, without any means to change prices etc.).