As the creative and interactive staff in my company are under my dictatorship... errrr care, I have had the opportunity to expand my understanding of what makes a great application in ways computer science can't teach you. I ran across a thought provoking article on A List Apart, that although targeted towards designers, could be generalized to any profession:
http://www.alistapart.com/articles/oncreativity
"Except for personal projects, self-expression has no place in design, but constraint is vital to design. No component fuels creativity more than constraint. Constraints are a designer’s best friend. They’re signposts, not shackles. Indeed, without constraint, creativity (and design) is irrelevant."