The "Microsoft Designs the iPod" video is still the best marketing video ever made.
Because it reflects, in a clear and visceral way, the impetus behind what I'd estimate to be around 90% of the unnecessary input into any marketing project.
It's the inability to push back on that input, what my friend Don Miller calls "being pecked to death by chickens" that ultimately dooms so many projects.
The impetus of the fictional Microsoft team-- and that of so many clients I've encountered-- is to create something bulletproof, something that answers each and every critic they've encountered along the way. That includes internal critics (e.g. the ones in their own heads) as well as external ones, critics with valid opinions and those who are just looking for something to say.
While the impulse may be valid, the result is not: each attempt to further explain and clarify just winds up muddying things even further so that the perspective consumer gives up rather than digs in.
I'm always tempted to show that video to the combined team at the start of any marketing-based project. It's a strong reminder of the dangers of ignoring the old dictum: when you try to please everybody, you wind up pleasing nobody.