That's understable, but lets see how this system works in X3: game create virtual sector, where player's ships are, without 3D space physic (even ships moves with a little bit wrong speed, their AI different). I don't understand how else can NPCs trade in real time with stations, if you said what sectors unloaded when player leave them.
So, if we can't give orders to ships for trading/patrooling sector/etc, we can't increase our proffit -> the game have a real limit. Building station will be expensive, but earning money for it may take a long time if we will trade by ourself. Trading in such simulators - is building a logisitc web with stations.
If we will trade only by ourself it will be looks like: buying [6kk energy] -> solding to 1 station [1kk] -> solding to 2th station [1,5kk] and etc. There is a high risk, what someone already sold them (so we loose profit, because our ship have heavy hull and low speed - a realistic for transporters). And 5-6 ships could do this work faster and reliable. That's why it's isn't usless.