The biggest problem with 3D, though, is the “convergence/focus” issue. A couple of the other issues — darkness and “smallness” — are at least theoretically solvable. But the deeper problem is that the audience must focus their eyes at the plane of the screen — say it is 80 feet away. This is constant no matter what.
But their eyes must converge at perhaps 10 feet away, then 60 feet, then 120 feet, and so on, depending on what the illusion is. So 3D films require us to focus at one distance and converge at another. And 600 million years of evolution has never presented this problem before. All living things with eyes have always focussed and converged at the same point.
3D forces our eyes to focus and converge at different points and that’s why so many end up getting headaches.
This is a deep problem, which no amount of technical tweaking can fix. Nothing will fix it short of producing true “holographic” images.
To me it’s simple: if something gives me headaches, that something isn’t a good thing. I’ve only watched one theatrical feature film in 3D: Avatar. The 3D didn’t ruin the experience precisely because the 3D effects were very subtle. I prefer the 2D version, which I also watched. I’ll be keeping my eyes open for developments in holographic display technologies. In the meantime I’ll be watching 2D.