The rules WERE changed after the USAir accident. Before that incident you were cleared to land without being told of the traffic on the runway in position. Now you are supposed to be told of who's there and what type, i.e. " Asiana cleared to land 24 left Southwest 737 in position". Southwest should have heard: "Southwest position and hold 24L traffic 747 on 4 mile final." Also, LAX local controllers were not clearing you into position on the runway with a long delay on the runway before takeoff but that has changed back in the last year. I HATE sitting in position on the runway for a long time. My seat cushion starts to get sucked up my @@@ the longer I sit exposed.
KLAX and all the other high volume airports will continue to have these incidents as long as they try to put 10 lbs into a 5 lbs sack.
For the most part ATC does a great job but it only takes a small loss of situational awareness to create an incident or an accident.