Great Project Managers are hard to find.  Great Technical Project Managers are even harder to find.  For most companies, hiring technical project managers isn't a long term plan.  There's a few typical problems with the world that revolves project managers:

• Companies hire an IT Project Manager, then the projects get completed.  Then they lay off the Project Manager.
• The Project Managers get bored, because let's face it, the projects are boring.
• A lot of roles that not typical of a Project Manager, get stuffed in the role.
• Didn't plan out the position well, as most don't know how to manage technical projects if they've never done it before.