Design is the communication of the planned or actual form and function of a product or service of value.
Communication is crucial and it is driven by leadership.
Consider these situations. Firstly, a developer building an application for themselves. They are the business leader, the subject matter expert, the designer, the developer, the tester, the project leader. There should not be any miscommunication, the only avenue for sub-optimal design will be the person’s skills.
Then there is the team of 7 developers, 3 testers, a consultant BA, a UI specialist, a support team off-shore, 3 business leaders (because different departments sponsor the project), and a set business subject matter experts with a myriad of vested interests, egos, experience, interest and conceptions about the profile of a poorly understood user group. Also, throw in that most of the business involved don’t have much understanding of the economics of agile methods.
From this group, one design must emerge and evolve.