Interaction design and Pixar: "Both of these techniques really drove home for me the importance of creating interactive prorotypes. Ya never know what ya go until you see it in action. Time is one of the elements that we as interaction designers manipulate. There are many aspects to time that can greatly effect the aesthetics of an interaction, the usability, and the overall experience, and if you are just using wireframes in your design models then you are not getting enough of the elements of your design reflected back to you so you can better explore it and hone it."
We see this all the time with mobile: you can't tell how well something will work until it's sitting there in your sweaty palm.