One of the most important aspects of product development is communication. From time to time you realize that people's expectations and views within a project can drift apart. Although everybody agrees on the same goal, the actual project might develop a little bit like this...
Software development can be a very artificial process and there is good reasoning why the sketch might have made you smile. The important part however is, that it doesn't have to be like this. From mockups we learned the value of allowing clients, users and the whole team to get an idea of how the resulting software might work in the future... not only does this help us to indicate the flaws of our design, we also through this process, that the actual piece is what the client had in mind, that we are following the same goal.
A long time ago we started to integrate mockups into the entire product development cycle and the results are great. The site http://getcoffeecup.net for example is a pure mockup. The product doesn't exist, yet by designing its box upfront it allows us to find out how much and where we have to invest to make this project a success. This mockup allows us not only to communicate the idea, but almost the entire project as it almost be finished.
Today we launched CoffeeCup, a software project we just started. However many artifacts we found important have been rapidly polished to communicate our mayor contribution points. Naturally this is far away from perfect, but that is the intention. Similar to most mockups, this is a playground nonetheless.