While it is true that our eyes' horizontal field of view is close to 180 degrees, we can't really "see" that much at once, especially if we are talking about reading.

Watching and reading are inherently different processes.

While reading, you will actually be focused to a very limited area at once. You will constantly move your eyes as you keep reading the text, regardless of how wide the screen is. A longer line requires more eye movement to reach the end of the line and makes it easier to lose track of which line you were at.

While watching, you don't have to make out every little detail in every single frame, so it is a good idea to make the aspect ratio of movies more like the way we see real life.

In summary, a widescreen movie is able to better utilize our "wide eyes", whereas wide text not only fails to better utilize them, but it actually makes text harder to read.

You might have to move your eyes left/right to read.

But it sure beats having to move your head.

If that were true, people would have Preferred landscape books to portrait books. They don't.

Holding and flipping pages on a landscape book is harder; furthermore, books are usually smaller as a whole.

When you open the book the two page spread is often landscape.

Do you actually read both sides? On a textbook, magazine or encylopedia, perhaps - mainly because a physical book doesn't have search features.

On a novel, it's portrait - you need paragraphs of context as you scan forwards and backwards to follow the information stream.

On a computer with text search facilities, it's more convenient to have vertical text results and paragraphs - as long as the width is acceptable.

Of course, TVs look better in a widescreen format, and computer screens have been forced to orbit TV display sizing for the past decade... and this is why we're stuck with useless 16:9 screens with not enough vertical pixels.