I actually rewatched one of my favorite "Simpsons" episodes on DVD last night ("The Front" from Season 4) and one of the little digs at "Best Writing in an Animated Series" caused me to crack up considering this thread.
For those of you who haven't seen it, the premise is that Lisa and Bart write an "Itchy and Scratchy" episode but put Grandpa's name on it to get it accepted (which leads to Grandpa's immortal line, "I did the Iggy!"). The episode ("Little Barbershop of Horrors") gets nominated for an award, and one of the cartoons it competes against is from the "Action Figure Man" cartoon series, specifically the "How to Buy Action Figure Man" episode.
Anyway, when I saw that, I realized that a lot of times, the best advertisement for a toy line is a cartoon or a movie to tie it into. I mean, honestly, the GI Joe cartoon was basically a big toy commercial and the real stories were in the comic book.
I guess what I'm saying is that with the downswing in cartoons these days (as I said earlier, do they even have cartoons on Saturday mornings anymore?), and the upswing in video games, not as many kids are watching to see any commercials nowadays. The majority of stuff I've seen in the last ten years has been print-oriented, so I wonder if the fact that there are/were new SW films led to the backing off on TV ads.