If you try different display options you will see that the width of the pages is designed around such a line length limit. They don’t shy away from going wider when they don’t show text (try Images) or from using a additional column (try Updates). This suggests to me that they know of the space they have, they just don’t want to fill it by mindlessly lengthening lines.
I realise from my own web design and development experience that this is easier said than done but on their scale and the problems that they deal with I don't think it's to unreasonable.