What our research and experience with executives in organization shows is that the reasons too many executives fail to serve as effective "transformational" leaders is that they lack the inherent traits to be transformational at all. You cannot teach a fish to fly. You cannot expect a high command and control, rigid, perfectionistic leader to flex into a change agent role. It is not possible.
Executive teams need a diverse range of talent and not every leader can adapt to changing organizational or competitive needs. That's why a wide range of talent on the general management team (and in the succession pipeline) is essential.