It would be dangerous to do an official board like you describe because you risk the fandom poisoning your IP. I think furry culture is probably the best example of this, a fandom that actually destroyed the original thing it idolized and turned it into something not only alien, but pretty repellent. It just takes a dedicated minority.

I think it would work if you pretty ruthlessly policed it to make sure you weren’t unintentionally providing a home for a lot of porn, and you required some kind of editorial approval before posting.

Apparently last time they played they were booed off stage for daring to play a song that criticised Hagrid.

Quite right too imho, Hagrid’s lovely.

I see a world in which people are making art for each other and telling stories to each other, where subcultures like fanfic flourish whether or not the original owner of the IP encourages them.

But I do think that if IP owners did want to encourage audience participation and fanfic and transmedia storytelling, it would really fly. eg. Imagine if the Harry Potter guys had set up a social networking type website for Harry Potter fanfic with ways for writers to collaborate on stories, comment on each other’s stories, message each other, highlight stories that got highly voted, and so on and so forth. I find Harry Potter fanfic a bit scary but you could imagine the fans absolutely loving it. And a fanfic writer might gravitate to that IP because the support was there.

I don’t think they actually intend players to be in anything more than a passive role, accepting the variety of content they push down and acting as buzz agents. I think we have already seen this with the Matrix franchise, which tried to make a consistent world with anime, console game, graphic novels, and movies all weaving together.