Paper Tiger asked: "I've asked this before and never got a satisfactory answer. Specifically at LAX (SEA, ATL and others) why are arrivals on the outer parallel and departures on the inner ? Swapping the usage would mean incursions such as this would be impossible."
The answer is really quite simple... using the outer parallels for landing allows for simultaneous instrument approaches. Using the inner parallels would not work as they are too close to each other.