As others have mentioned, whether a manager is technically inclined or not doesn't have all that much impact on whether he's good.
As a German psychologist and management trainer once said, most people either have people skills or organizational/technical skills. A good manager/boss needs both. And guess what, only about 10% of the population have an affinity for both.
This basically means that for every nine employees, you can have only one manager! And since you usually have more than one layer of management, you need beyond nine people per lowest management body to make that cut. I don't know about the US but in Switzerland, we sometimes designate a teamleader to a two man team.
There are just not enough competent people in existence to fill that many management roles. Simple as that. Simplify management structures. Use only those managers who actually can manage and weed out the donkey droppings. But seeing as, obviously, 50% of people are below average and some of those suck massively, that's going to be hard.