I have glaucoma, giving me the classic arc-shaped loss of visual field in each eye. Bottom line is that I really need both eyes at the same time to get a decent 2D view. Persistence of vision notwithstanding, alternately displaying images to each eye just doesn't add up well when each eye is depending on the other to fill in missing data. I can usually perceive the 3D effect, but at the cost of most detail in the middle of the image, and overall dramatic reduction in brightness vs. a 2d display.
I'd rather have a high quality 2D image than a crappy 3D one.