Considering that 2D movies have almost all the 3D cues needed for our brains to interpret them as 3D, I'm not convinced '3D' movies actually make that much sense. It's certainly not comparable to 'flying' vs 'not flying' anyway IMHO.

Oh, I haven't seen any movie that makes 3D worthwhile. It's just that the argument "people tried it before and failed" is not even a little convincing.