To use your movie example, this thread is more of.. seeing some trailers to a movie, liking what you've seen in those trailers, but then demanding that more of the movie be explained to you before you go out to see it, to make sure it's worth it.
Having concerns is fine. However, the proper way to approach those concerns would be to wait until it's out if you're having that many doubts. Then you'll get the facts from those that went ahead with a purchase on day one.
Ya... That comparison doesnt work either, comparing games to books and movies doesnt work anyway because they all have their own way with giving out information(SDCC show how the movie and book industry does it). Believe it or not, we had a lot of information about Guild Wars and Diablo prior to launch, specifically in terms of content. Yes, waiting is a good idea, specially with a new IP, but wanting Bungie to give information out like other companies is not a bad thing, and imo encouraging it only helps the gamer.