To contribute something to the discussion, I've read that the areas of the brain that handle the sense of touch are often completely rewired in the event of blindness to make it resemble something akin to 'sight'. It's sort of easy to understand why this is: both sight and touch give ideas to the shape and texture of an object, and are therefore more linked to each other than the other classical five senses. If you see a completely novel object, you're much more likely to hazard an educated guess as to what it feels like than as to its smell or taste. Touch is also the only sense which demonstrably increases in sensitivity in response to relatively short periods of blindness (i.e. a couple of days), as far as I can remember.
My increasing obsession with Katawa Shoujo has led me to 'experiment' - for want of a better word - with the idea of disability. I find myself trying to get dressed without using my hands (bloody difficult, but easier with elastic objects like T-shirts and tracksuits) or with my eyes closed (you can tell which item of clothing is which by their texture because I know them by sight), amongst other everyday tasks. My 'research' has led me to conclude that living in dark is something a lot less terrifying than living in silence. Blindness can be compensated by sound
and touch, but once your hearing's gone, that's it. There's really nothing else that you can use that mimics tiny hairs in the deep canals of your inner ear picking up the sensation of waves vibrating through the air with exquisite precision. While you can hear sounds coming from every direction, sight is limited to the narrow funnel of the direction you happen to face; so to me, blindness would be easier to cope with than deafness.
Man, talking about all this makes me feel so fortunate. Here I am, living a healthy, wealthy, happy life while there are millions all over the world struggling with disease and disability. It puts all my problems into perspective. It's a good mental slap in the face when you're feeling depressed about some stupid, trivial detail to think about the things you have that so many more people would appreciate so much more than you.