Why come no one is seeing the 2D screenings of today's 3D Movies? (i.e. Gravity & 47 Ronin)

[game_on]

If I have a choice, I pick 2D. 3D doesn't add much to the experience for me and some people I go with to the movie get sick watching 3D. A theatre I go to charges 2 euro extra for 3D by the way...