Perhaps it is because I enjoy social interaction but surely there would be nothing more dull than conducting an interview purely based on a set of structured questions with every candidate being "processed" in the same way? Working for your company, no matter in what role, will require some sort of social engagement at some point in time and so shouldn't this be assesed in an interview? 

I really object to the formality a lot of interviewers use and always recommend to our clients that they should make interviews and enjoyable and natural process for both parties. Beyond my strategy of disarming candidates with a warm start to our engagement, it just makes the whole process a more pleasant experience. It also builds trusts more quickly and, I believe, makes candidates more open and honest. The way you conduct an interview should represent your Employer Brand and give candidates an insight into your company culture. I am not saying it should all be fun and games but it should be an enjoyable and engaging experience that is set up to allow both parties to assess one another with all the facts on the table and this includes a feel of behaviours and culture.