The more time I spend reading things on the internet, the more obvious it is to me that measure matters. Too many sites still have lines running to well over 100 characters. (I saw one recently that runs to 135, and many online technical manuals still run to the full width of the page!) It’s just hard to read.
I locked this site in at between 66 and 72 characters, and it makes a difference. I hope, eventually, that everyone gets this right. In the meantime, Instapaper and Readability carry the day!