We all know how hard change can be. Whether we like to admit it or not, every one of us performs at least some parts of our jobs on auto-pilot; it's more efficient for our brains to operate that way. That makes it hard to do things differently.
When leaders introduce a significant change without a lot of communication around what will be different, why it's happening (including connecting it to something that matters to each member of the team), and how the change will unfold, they shoot themselves in the foot. They inevitably encounter a lot of friction if not downright resistance to the change. In the best case, this slows things down. In the worst, this has led to multi-million dollar failures.