I had one of those a long time ago, specifically for doing typesetting work. It was great being able to see a whole page at a glance. Of course, with today's computers, many LCD monitors can be easily rotated to be used vertically if you desire, even though most people don't do it.
Originally Posted by Nick Zentena
For books and magazines, the vertical format is just easier from a production and handling point of view; horizontal books are harder to hold. Books have been made that way since the invention of the codex. For art that's hung on a wall, I suppose that's not so much of an issue.