Part of the problem with improving peripheral vision is that it requires not just changes to the eye, but changes to the brain as well.
We're not usually consciously aware of it, but we only have clear vision right in the center of our field of vision, in a very small area called the fovea. Our vision away from the fovea is almost unbelievably awful. Visual processing is one of the most intensive, processor-dependent things our brain does, and more than 80% of the vision-processing neurons in the brain are dedicated just to the central 7 degrees or so of our vision (and about half the nerve fibers exiting the retina carry information from the small area in the middle). You can train yourself to recognize how terrible your vision is outside that very small space in the middle, and when you do, it's rather...err, eye-opening.
So improving our peripheral vision would mean throwing a massive number of new brain neurons at the problem. That's unlikely to happen, for a number of reasons.
