I would say Kanban is the opposite of keeping your head down - you have to come up for air every time you finish something and priorities can change each time. Waterfall is the classic head-down approach, work on something for months/years and then release it and see if there is still a market for it. I think there are strong tendencies towards waterfall in many tech personalities - "I'm just going to disappear and come back with something brilliant at some unspecified point in the future." People don't want to feel that they're building widgets when they could be making a cathedral but that's often what is needed. Agile and Kanban fight this tendency and are therefore not always popular.