As Tom said on the show, "...there's a disconnect between the decisions we are making and our understanding of why we are making those decisions." He says it's because designers are so good at what they do. They do things subconsciously from years of training, but often fail to connect the dots for clients so that they can accept the ultimate design.
The ability to effectively articulate design decisions is critical to the success of a project, because the most articulate person often wins!
Learn the steps Tom takes to explain the value of design to non-designers (aka clients), and have them give buy-in.