See here's my thing with the 3D, and I don't know why titanic is finally the one that broke my back.
I disagree with the idea that technical advances in film over the last hundred years have been made to put you there with the characters. Perhaps emotionally, that might be the end game. But up until this point, that is not what has literally been happening to film form.
First we had standard, single images. Electrocuting an elephant, arrival of a train, etc. Cinema of attractions, that kinda thing.
I guess you can call editing the first big advancement. But editing isn't putting you in the character's world. It is putting the characters in their own world. It is giving them a story and a realized universe to play it out in.
Then sound. Sound is literally giving the characters a voice. It is making them sound and act more like us. It is making their world richer.
Color and widescreen, I can kind of agree with you. It is more of a visceral experience for the audience or an expansion of film art, than an actual storytelling tool. But color and widescreen do not actually change your relationship with what is happening in the world of the film.
BUT 3D DOES. It is, literally, breaking the fourth wall of the film...and in the case of the titanic, for no good reason. And standard narrative film, by its nature, is a projected image of events existing in another time and place...self-contained in their own world. The magic of film is that I can be transported emotionally through good storytelling and this bizarre concept of film editing.
These two things contradict each other. Something happening in the same room as you, and something happening off in another world. You can't have both at once. And every problem I have with 3D stems from that. When Rose is floating on a door saying her goodbyes to Jack, even if I have to devote one ounce of brain power into processing that her elbow is closer to me than her head...it is too much.
I agree with dorkman that if 3D becomes the next thing, our film grammar will definitely have to change. But I would even go as far as to say our storytelling may have to change to adopt more of a meta feel. To acknowledge the audience's presence.
To date, the best thing I have seen in 3D is the spidey ride at universal. And while it is really cool, I would prefer to not have our films evolve in that direction. I enjoy a good, old-fashioned story.