How do you live with a centered fixed-width table that is wasting 15% of the browser window with nothing but hectares of white space then? Bumping the line-height to 1.5ish the font size has minimal impact to space efficiency, and add tons to readability.
We're talking about just 1.5x line height. Which is a perfectly reasonable default for nice reading. The browsers have a lower default line height because of historical reasons, doesn't mean it's the right one. People don't use the Times font very often either.