TLDR; The biggest problem with 3D, though, is the "convergence/focus" issue. A couple of the other issues -- darkness and "smallness" -- are at least theoretica

TLDR; 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. While I agree with this, I've to say I generally prefer 3D versions of the movies for that extra oomph. There is no particular reason left to visit theaters otherwise. Especially it's just super cool on IMAX (I mean "real" IMAX). Movies like Space Station 3D would miss out on too much fun without being 3D.