I am also surprised that users keep it turned down so low. Personally, I like the light and generally have it at 14-16 and turn it down to 10-12 at night with no light.
If I was not going to use the light I probably would still use the Kindle Keyboard. My wife still uses hers and the screen is much better than either the Touch or the Paperwhite. The background is much closer to white than the gray of the Touch and Paperwhite. The only saving grace of the Paperwhite is the front lit feature.