As you mention, binocular vision is lacking in a surprising number of people and until recently this was thought to be uncorrectable if not treated while the child was still young. That turned out to be not entirely accurate.

Those without binocular vision can have a fairly large range of non-specific symptoms and perception problems. There is an interesting discussion of the change in understanding in this link. http://www.strabismus.org/all_about_strabismus.html