My understanding is that the inner runways are used for departures priimarily due to noise abatement - keep the noisy takeoffs away from the airport boundaries. At LAX the gotcha is how close the runways are: you are entering the inner parallel almost as soon as you exit the outer landing runway.
Anyway, with the frequencies and facilities as overstretched as they are there would still be incursions if arrivals were on the inner parallels.
Be careful.