Daniel Engber discusses why 3-D movies, which briefly seemed about to shove 2-D out of this dimension altogether, are now dying out. Probably the same reason they didn't do that the last time such predictions were made, back in the fifties. If the movie's good, people don't care if it's in 2-D or 3-D and if it's not, then 3-D is a gimmick that only takes you so far and costs you more money.