I have seen several movies in 3D and, after talking to my friends, most of them didn't need to be in this format. To me, 3d is an option for movies that have pretty awesome special effects, of the visual kind, to enhance them but, just because the movie look good, doesn't mean it have to be in 3D. However, this phenomenon is going so fast that it starting to become a normal thing.
There even a rumor, or fact, regarding the remake in this format of a certain big blockbuster movie about the sinking of ship due to a crash with an icicle in the middle of the ocean.