Why Aren't We Teaching This?

As an avid blog reader, writer, and teacher I see comments and questions about employee engagement, reducing turnover, keeping critical staff and reams about leadership. Whether leadership is born or taught, trying to define it, etc.
When you look at the syllabus of the typical MBA program that is very little in it about how to build and lead teams. There is plenty about finance, accounting, marketing, and even a little economics for texture, but very little about people.
Do we think the transition from doer to leader occurs by osmosis? Do we believe that it is "embedded" in the right candidates and it will emerge?
I read an article a while back that indicated that 40% of new managers fail within the first 18 months and the biggest reason they fail is that they don't know how to build and maintain effective relationships.
When I work with entrepreneurs one of the biggest obstacles they experience is moving from doer to leader and building successful transition and succession strategies.
Executive and personal coaching as businesses are booming. It has become the therapy of the new millennium. Why are companies and educational institutions not addressing this earlier on in peoples careers?
I know that there are books out there like Good to Great and the One Minute Manager, but as a recent B school grad asked- "So what is this bus that Jim Collins keeps talking about?"
At the end of the day everything boils down to effective relationships. Isn't about time we recognize and embrace that?