I think it’s important to add that this isn’t unprecedented. When the Academy awards began in 1928 there were 5 nominations for “Best Picture” and 5 more for something akin to “Best Artistic Achievement in Film” or something along those lines. In other words, best artsy flick. Over the first few years these categories bled together until, by 1933 they had 10 nominations for Best Picture (or whatever they were calling it at the time). This was in a time when there were far fewer movies to select from and that led to similar complaints that unworthy films were being selected.
They paired it back to 5 pretty quickly. By 1944 (the year after they got it right for the 1st time) they were back to 5 films and that’s where it’s been ever since.
That caveat aside, it is clearly an attempt to gain ratings. Nobody in the know had any illusions that Avatar or District 9 were going to win (thank God), but a lot of people who might not otherwise have followed the Oscars tuned in convinced that somehow one of these crapfests would be the first sci-fi to ever win Best Picture.
Apparently it worked because ratings were far higher. It probably helped that they took the whole “get somebody to host the show that doesn’t suck morbidly” thing seriously. It pissed me off when I first heard about it, but anybody who follows the Oscars could have paired it down to the five that were the “real” nominations (Inglorious Basterds, Hurt Locker, A Serious Man, Precious and An Education) and which were the fluff to attract viewers. If it works, power to them. Ratings on the Oscars had been in free-fall leading up to this and it doesn’t cost any more to nominate a few more flicks.