You meant during the results announcement, right? Not during the actual competition, I'd hope. I'm not surprised people would leave during results announcement, as the results were very predictable for standard this year. At least for the top 4.
No, the number of people in the room for the dancing itself was significantly down after the Rhythm result was announced and the people who had come for that had left the room.
This year it would have been a much better choice to run the American style events after the International style ones, as the American styles had much more excitement and audience draw/appeal surrounding them.
I think it would have been even better to interleave the events, so that the finals of both styles are danced back to back, at the end. People kind of got tired at the end, and the results WERE predictable. Though it's a pity, because the dancing was excellent.