Strategy can be creative too.
Design is only the outward expression of a project's goals. Behaviour and mindset change both within and outside an organisation takes a lot more. Design teams should be part of a deeper engagement. Take the time to truly understand a client's world. Do interviews, with everyone from the factory floor to the CEO. Gather perspectives. Think creatively about the insights that start to emerge.
A 'big idea' can and should emerge before any designer opens a Mac. I believe that approaching the brand strategy and positioning with a creative mindset will get you half way to a great brand idea.