I oversimplify both the MS and Apple examples as the "builder vs. caretaker" pendulum. Though Tim Cook could hold the reins for the next 10-20 years, I have no doubt that Apple will transition to another builder in the future. Once per generation? Every other generation? The computers (plural, laptops, PCs, phones, etc.) industry is still young.

Eight years post-Jobs, it remains to be seen what Apple's evolutionary thrust turns out to be, Amelio/Sculley. For now the market expectations (user desires) would seem to support innovation and design as a business priority.