I feel like everyone savvy just does this because they understand the consequences of not doing it and the clueless people always just bitch about there being so much office politics. In my experience it's just the communication protocol that works.
It's not so much politics as it is the fact that no one likes surprises, particularly not your boss or your boss's boss. Almost every major people-problem I've had to sort out in the past year has been a result of someone not getting buy-in from their team or superiors before proclaiming a major change. Change is good, everyone wants you to make your awesome improvements, but you're not a cowboy. You have to engage the people who will be affected by this change, collect feedback, and address any concerns that are surfaced.
