IMO, it's due to a couple of factors:
1) LA has to be the biggest frontrunner, bandwagon fan city in all of sports. We all know that and can debate the reasons why, but it's true. Those of us born and raised here know it better than anyone else.
2) In regard to specifically the court side seats, they're all season ticket holders, but some of them are held by individuals, while many of them are owned by corps ... studios, agencies, investment banks, etc. Many of these people go out to one of the "super secret" rooms/clubs at halftime. I think the one where all the stars go is called Purple and Gold, or something like that. When it's a real crappy game, I think a lot of people stay at whatever bar they're schmoozing at and watch the start of the 3rd on TV. If it goes downhill quick, like the Seattle game, they probably take off early.
I was at that game and it wasn't just the courtside seats leaving. A lot of wheels are falling off of the bandwagon right now. It bothers me a little bit, but over the years I've learned to not let it bring me down. I love going to the games and always will, I can't really worry about everyone else. I almost like it b/c I know I can upgrade my seats each year. The first five years I had season tix; I would request an upgrade every year and get denied. This was the first year I got one ... it's not much, just two rows closer, but next year I think I'll be able to make a good move.
Even though LA is the biggest bandwagon fan city, there are also a ton of great fans that are knowledgeable and loyal to the team no matter what. Many of these fans are simply priced out of the market, which is a problem in the entire league, not just LA. It's unfortunate, but I don't see it changing.