My wife and I recently went to the cinema to watch Tron, recently as in a month or two
At the start of the movie there is a disclaimer that some of the scene's were shot in 2D and that this was intentional.
Firstly I should state that, as far as 3D movies go, it was the best done for being accurate. I find many 3D movies just don't look right, as especially in fast scene's. It's as if each image becomes out of sync and the 3D effect either partially breaks or fully breaks. This didn't happen once in Tron.
With that said, it was near impossible to tell the difference between the 2d and 3d scene's without removing your glasses to see if the screen was blurry or not.
2D pictures provide a lot of depth information and I think movie producers underestimate this.
I think if 3D is to be sucessful, movies should not focus on producing screens that are in perfect 3D. But they should use the ability to use 3D images as a plot device, or to get a cheap 'jump' from the crowd as the car comes out of the screen to hit them.
I remember that "Sin City" was mostly in black and white and that they used colour to represent smell. This would also be a good use for 3D. Imagine a sherlock holmes movie and when he is looking for clues it goes to a first-person perspective. Everything Sherlock focuses on, becomes 3D with the rest of the screen as 2D.
I don't think there's a healthy issue with the glassless 3D TV sets. I think the news about possible health issues is just companies being "Prudent". They can't be blamed for trouble, if people are warned of "dangers".