[DigitalJack]

As a counterpoint, plain and boring is not inspirational. If you are working on an app, and the appearance is the bare minimum of functional, you aren't likely to get any kind of feedback inspiration from that part of your own creation.

Creation, whether design or development, is an iteration of making and discovering. As you work, you discover new things along the way. As you work, your creation gives you further inspiration. Your thinking branches out in new ways upon seeing what you have made so far.

Beauty is inspiring. If you are focussed solely on development, you may lose out on some of that. I know code can be (and hopefully is) beautiful, and seeing a clean implementation is inspiring too, the user facing portion should not be a second class citizen in the creation process.