In my career, I have heard the quote “Consistency is the hobgoblin of little minds” when a client or business owner wanted to do something new, often for the sake of doing something new. The full quote by Ralph Waldo Emerson is ““A foolish consistency is the hobgoblin of little minds.” There is a very important distinction there.
Consistency is essential to reducing the cognitive load of your interface – the mental effort required to complete a task. When a design is consistent, every interaction feels smooth and frictionless. When it is too inconsistent, the user must expend unnecessary effort figuring out the interface instead of completing the work.