Did you know that on average, conference attendees only recall 10% of what they learn? Talk about no return on investment - what are the chances that these attendees will keep spending the money to come back year after year if they aren't absorbing the information?
Face it - your brain is not designed to sit passively for 8-10 hours a day listening to presenters droning on about information you probably should be paying attention to because you paid to hear it.
A quick way to get that boost in brain power is to get attendees moving. Your brain craves movement and physical activity, and studies have shown that under such circumstances, your brain develops at a much more rapid pace. We are social beings; Sitting in chairs all day with little to no interactivity or communication amongst peers is possibly the most counterproductive thing we can do.
Another simple solution is to structure conferences and meetings in a way that can be associated with some sort of emotional experience, context and meaning, leading to better recall. To really drive important points home, schedule structured time for attendees to interact and discuss with one another, re-exposing others to the information and increasing retention by tying the information to an experience.