You go to the movies to be engrossed in the experience, to suspend your disbelief. The glasses have a reflection of the screen in the corners that is basically the movie playing in the corner of your eye. It's bad enough that people distract you with flashing cell phones and ipods but to have the entire movie playing in front of you and your periphery is not the way you want to spend two hours.
"Why are you so M* f* blurry" ... I'm not sure what causes this, but while watching Avatar I noticed that when things became very fast paced, you almost could not focus on anything. All of the images on the screen began to blur. Seeing Avatar in 2D, there were no issues with the fast paced action. Might be the way 3D is filmed that just can't handle scenes like that.
Color ... Avatar was an amazingly rich environment with more colors than you can shake a crayola box at. 3D made Avatar seem muted, washed out. In 2D you could see every little floating seed and fleck of burning tree.
It's not just the big screen that is lackluster. 3D televisions leave a lot to be desired also. 3D was big in the 50s and has attempted to make a strong come back. Watching television with extra equipment is not something that most people handle the extra equipment. The technology has to get to a point where you don't need the additional accoutrements.