With the rise of the non-traditional agency comes the rise of departments and specialties and "practices" that didn't exist just a few short years ago. Where agencies used to be creative, account and media, you now have to throw into the mix interaction design, planning, mobile experts, social media mavens, flash specialists, analytics and more.
What's more, each of these tribes are told that a great idea can come from anywhere. Thus they feel they can sit in judgment of the ideas that emanate from the agency. In short, ownership of ideas becomes individualized rather than collectivized. The agency, at least at the early developmental stages of idea development, seems to say "that's not our idea, that's your idea."
Maybe I'm wrong about this, but despite all the politics and in-fighting that afflicted agencies in days of yore, there was some portion of rallying around the work.
Now work isn't isn't owned by the agency--it's owned by the individual who created it. When things don't go well, you're out on your own. If work goes well, then you have friends.
I think Casey Stengel once said, "The trick to managing a baseball team is keeping the ten guys who hate you away from the fifteen guys who are undecided."
The trick to being a successful creative is keeping your insecure and negative impulses away from the impulses that are undecided.
Some days that works. Some days that's hard.