Hmm, my first reaction was the same as yours. But I have quite bad eyesight and looking at the "regular 400 at 16px" example on the page reminded me that I definitely sometimes find myself squinting trying to work out whether a character is a parenthesis or a brace (Droid Sans Mono). So I suppose it'd probably be quite helpful to have a brace that's very visually distinct from parenthesis even if it's not particularly pretty on its own.