I'm not sure people don't do that. Certainly, gawker isn't very valuable, but e.g. Myspace data (analysed at e.g. http://www.schneier.com/essay-144.html, money quote: "The most common password, 'password1,' was used in 0.22 percent of all accounts". I'm sure you can find the original file if you look hard enough) suggests that weak passwords are still quite common at presumably-valuable sites.