Mithrandir said:
J J's Paranoia comes from his own mindset, in which he believes that plot-twists and surprise are the most important elements of a cinematic experience.
Faust, Oedipus, The Illiad, Dante's Commedy...most of the major works of art Men have created have quite predictable endings, we can foretell what will happen, but we don't know how will it happen, and the depth of these works is set in that how. The Prequels sucked, not because we knew the story already, but because they were shittily told, in every single way, from script to visuals.
Now, Star Wars redefined the concept of plot-twist with "I am your father"... and it was cool, because it was jaw-dropping but also because it presented the opportunity to make personal for the character a struggle that was mainly political. It was fine for a 3 part movie.
Now there's a virtually unlimited number of movies, and it should be time to realise there's a lot more to tell in any story than deus-ex-machina-kind of stuff. I mean this diegetically, and non diegetically, a film is perfectly enjoyable even if you know everything that will happen.
JJ only believes in Jaw-dropping amusement. Lost proves this, and that is the source of his secrecy. It's funny he is compared with Spielberg some times.
I just watched the 'making of' Jaws documentary on the Bluray, and it sounds like they had a ton of secrecy for that one, too. In that case, it was because they had a big, crappy mechanical fish and knew that seeing it in stills, in the garage, would lead to huge doubts about the film.
I imagine JJ has reasons like this. People will freak out unnecessarily about each and every piece of information they get about the story or how it's being filmed (especially far in advance of it being completed).
Don't get me wrong, JJ is also infamous for relying on surprises. The need for Cumberbatch to keep his mouth shut about his role in ST2 was downright absurd. But so long as his intentions are just to get a bit of extra buzz around the theatrical release time, it's not a huge deal to me. The concern, of course, is if those surprises are required for the film to be enjoyable at all. A movie can't be successful in the long term, for re-watches, etc, if that's the case.