The whole 3D thing has already passed once before, and now with newer technology they're trying again. Give it time and it will fade away. However like most people say, a bad movie is a bad movie regardless of 3D.
The main people to blame for movies going on the decline would be the public. If we respond even slightly positive to a movie, even if it was mediocre or bad, they take that information and use it to heavily influence their next movie. Hollywood is just milking the public. Granted not ALL producers are but a great majority of them certainly do it. 3D is just one way they figured out how to get a bit more money from us.
IMHO, I think CG has ruined cinema.
-High fives for everyone who agrees.-

.