Social engineering. If I have access to your browsing history and I see that you frequently visit, say, BoingBoing I can pretend to also enjoy visiting BoingBoing to establish a connection with you. Once we've had a nice chat about the latest posting and you've relaxed a bit I can start steering the conversation towards a particular topic.
Identification of relationships. Replace "whether someone was a member of an organization or not" in the approach described in that blog post with "visited the same websites" or even "visited the same websites at the same times" as information that would be easily accessible from a browsing history corpus.
Blackmail. Even if your browsing habits are fairly tame and all the sites you visit are legal, are there any sites that someone could show up at your place of business and list that would cause you embarrassment or cause some of your customers to stop doing business with you? I'm sure your boss would be surprised to hear that you've been spending a lot of time on job search sites, for instance.
Future reference. What's legal today may not be legal tomorrow. Suppose that the Internet and this Snoopers Charter had existed in the early 1900s in the United States. When 1920 rolls around, Eliot Ness goes back to his record of browsing history to identify people who had visited websites about home brewing of alcohol. Many of the people who visited those websites may have stopped brewing due to Prohibition ... but it gives him a nice list of people to check to ensure they're staying dry.