They won because the products (messaging) are identical, the customers (people over 13) are the same, the distribution channels (the Internet) are the same, and because Facebook has a huge recognition in the social media sector (matched in the survey only by Twitter) and many many users (despite the fact that people can sign up for more than one account).

Facebook aren't asking to police all uses of Face*, they asked to stop a specific trademark for a single product.

The end of the report says something along the lines that Facebook can expect to win an opposition if the Face* thing can be argued to be related to something Facebook actually does and if there's a significant portion of a survey that associates it with Facebook (30% is not low). So Faceplanting is fine, but Facetalk, Facemail, Facefriends, Facephotos are probably things Facebook can oppose and win if they haven't been trademarked yet.