Short answer – is it necessary – no. Some people are more creative when mental models are challenged, some just shut down. Head butting is probably overstating it, but respectful and constructive debate is useful. We need critical thinking and analysis, so we don’t end up with group think and head off down the wrong path.
People don’t resist change, they resist being changed. Most people are in a state of constant change in their lives, but they are in control of the type and pace of that change. If you can work with people, help them to feel more included, then you may find no reason to act like silly goats.