Change may not become part of the culture before focus shifts. The change may roll back a few months after leadership changes focus.
Loss of political capital: because the change was less inclusive up front, political capital is lost.
Job security for the leader: if the change does not provide the benefit expected, or otherwise fails, the people who mandated the change may lose their job. (Aside: setting this expectation is definitely a bad way to manage, as it creates huge incentives for leaders to make the change look like it worked.)
Opportunity cost: other improvements may be needed but everyone is tied up working on the mandated improvement.
Not necessarily a “good fit” for the organization: the current situation was likely not understood well, so the solution applied often leaves pain points or gaps.
Often treats people like robots.