'Oh, I see' is not something you would expect to hear when a highly myopic person receives proper eyeglasses at a doctor's office.

Rather, 'Oh, I see' is typically used to communicate comprehension. My take is that vision and the act of seeing are in so much idiomatic language because this is the predominant sense by which most people encounter the world. The dictionary definition of 'see' includes an entry for 'recognition'. 'Hear' does not have this dictionary meaning.

Perhaps vision is a better mental metaphor for general recognition, realization, and cognizance. However, people will say 'I hear ya' to imply much the same thing. That's all I can think of, but I'm not an etymologist or psycholinguist.