There are Storm promotion going on too. Slater was on one pilon of the bridge, Hayne the other.
All the attention is good for the game. People have been whinging about the lack of support for NRL in Sydney, and how AFL does it better.
The main reason this didn't occur last year but is happening now is that the NRL are trying really hard this year (and hopefully in future years) to make grand final week an event, to make it a spectacle they can sell, which helps the game.
They were talking about it before the season started, so it would have happened regardless of who made it.
EDIT: On the media side, News Corp is promoting the Sh*t out of this grandfinal, trying to help the NRL generate interest and make grand final week an event. In Sydney, it is obviously Parra related, but in Melbourne the paper is really getting behind the Storm. Good. Why can't they do it all year is my question.