Amazon recently redesigned its site to make it more "tablet friendly."
http://techcrunch.com/2011/09/02/ama...arriving-soon/
It is in vogue right now to use a flexible format that scales to different window sizes. In theory, if you do it right, you can have one site for computer, tablet, phone. So that's a lot less work than maintaining different sites. But I do see that when I tried to make the window smaller, the columns did not resize properly (this was on Firefox on Mac). Also, it's possible to make a column that flexes in width and still give it a reasonable maximum width.
I agree with you that the reading columns are far too wide for a computer screen. This morning my daughter was reading an Amazon review out loud (about Sea Monkeys!) and she had a difficult time finding her place on the next line. Amazon does extensive A/B testing so I'm surprised they are doing such a poor job on this.
eP