From the US, Emily Chapman at The Owlfred Chronicles has a post on university social media presence, and suggests that universities are often slow to embrace that whole malarkey :
Universities can be slow to embrace social media, and it’s to their detriment. Not only does having a weak social media presence open up a school to looking behind-the-times–it allows students to control a school’s image online. Unfortunately, the students who shout (or tweet) the loudest are often less-than-happy with a school.
Social media can be a strange new world for university staff not used to a generation of students for whom going without Facebook for a week is a huge struggle. However, if a university doesn’t stay on top of its image, its students will step in to fill that void–and they may not convey the message a university wants affiliated with its name. By taking advantage of pre-existing Twitter accounts and a Facebook-savvy student body, schools can easily increase their social media presence with minimal effort.
Along with the fact that if you don’t have social media profiles, someone could make a joke one which receives a lot of unwanted attention, this is one of the most important reason for universities to have a presence. Having said this, it’s a largely negative justification: a defensive position against others on social media.