In a word, because it’s social.  B2B marketing norms are based on professional / commercial interactions – not social interactions.  B2B marketers (I count myself here) have operated on a different basis – our interactions, while they can become personal, are a little more formal and a little less frequent than those in the social realm.

So when you tell a B2B marketer to use social media it’s a little bit like telling them to take their clothes off.

But the evidence that social media works even in B2B is there. Adoption will be slow, but it will happen.