I had this same discussion on another HN thread a while back. I prefer lines to run as long as possible; I find it difficult/distracting to move my eyes to the beginning of the next line every few seconds. I'm sure I'm in the minority, but I have to believe I'm not the only one out there who feels this way.
Rather than having the website author wrap lines at a width that works for the average user or use case (which may only be optimum for a percentage of users or use cases, which may not include me), the user can simply make their browser whatever width they prefer the lines to wrap at. This way, everybody gets to choose what works for them.
Making the browser windows narrow is a bad suggestion. Because most websites have some sort of navigation bar on the left and another bar on the right, so we need a wide enough window to get enough of the main text (width).
There are very few websites without those columns.
> I find it difficult/distracting to move my eyes to the beginning of the next line every few seconds.
You must find it difficult to read books, magazines, newspapers, as all of them have short lines
I am in the same boat as GP, and I wonder if it's one of the reasons I migrated hard to ebooks and online magazines/newspapers as soon as that became possible and never looked back.