I've got a screen that is much wider than it is tall, this throws away so much of it. It's as bad as Facebook, where the stuff you want to see is a band about 1/4 the area of the screen.
In theory sites could optimize for wide screens by adding columns, but 1) its a very small audience 2) most content is not suitable for that (how would you scroll a feed that spans 3 columns?)
That has a small number of long columns down the entire page, which doesn't give any of the benefits of having columns. Actually, it's only worse in terms of readability, as a big factor is how well your brain can spatialize the location of what you're reading for backwards jumps or subconscious memory palace stuff. Here that's complicated by the mental overhead of "I'm halfway down the page, but the page is really twice as long as it is, so that's actually 1/4 of the way through."
Proper column layout involves limiting columns to screen height, probably by paginating. Then the reader can perceive the text as a tree of Page > Column > Paragraph > Row. Tangentially, I think there are studies positing that this, helped by the notion of physical pages in space, is what's behind the readability advantage of books.
Alternative to pagination is scroll-direction: horizontal. Now the experience is even closer to reading a book. And to Windows 8! IMO there's a shortage of novelty sites with true (non-slideshow or carousel) horizontal scrolling.
Hope you don't mind the self-promo: Here's a GH project of mine which attempts to provide styles for popular websites to remove large paddings and max-widths: https://github.com/phil294/density-userstyle
browsers have been working on multiple column text for a while now[0], so by employing a container/media query, you could have multiple columns for wide screens and content containers. i experimented with it a couple years ago and found quirks (which i can't remember offhand) that made it not quite ready for primetime then.
