The LAX schedule seems meant for people who want to nap on arrival (or in the late afternoon/earl evening) and hit the late LA dinner and nightlife scene on arrival night and on the night before departure.
Sort of more seriously, it's hard to have a better schedule for ARN-LAX/LAX-ARN if wanting to have some decent feed to/from both ends of the route. The distance and time zone differences are such that it's a balancing act unless wanting to really negatively impact fleet utilization.