I don’t know of any research off the top of my head that would relate the changing age profile in our society to failure of leadership and I haven’t really looked very hard, but
here’s my line of thought:
– population demographics are such that we have an ageing population
– political / social leaders are now reaching leadership positions when they are older (cf age of famous political / military leaders in history …)
– because people are living longer (and because of the loss of a reasonable percentage the world war 2 generation of males ?), baby boomers reached leadership positions sooner, with less basis, and occupied them for longer
There is now a mismatch between peak of intellectual / motivational / creative force so that potential energy for leadership is lost and people develop wisdom and / or cynicism before they get an opportunity to practice energetic leadership.
In the emerging model in my head, the peak of focussed, driven intellectual energy maybe around the age of 30 to 35 … when potentially great people know enough to lead, but don’t know enough to have doubts.