I didn't really answer David's main question, did I? Are there too many middle managers?
I suppose it would depend on how much autonomy they and staff had. Once the layers of accountability and approval start to pile up, I'd say you've hit the "too many" mark.
We've had a question in our federal employee survey for 13 years that asks employees whether they feel that "the quality of my work suffers because of…too many approval stages". In the most recent (2011) survey, about 53% of managers/supervisors said "often" or "always", while 43% of non-supervisory employees said the same.
There was a steady increase with tenure in the proportion of public servants who said that layers of approval was bogging down their work. That may be because those with more tenure are more likely to be managers/supervisors themselves, but it may also be because they have less patience for having to wait for someone's approval, given that they have been competently doing their job for X number of years. I'll note that both of these patterns (tenure and manager/non-manager) have held constant over the the last few survey cycles.
Response patterns also varied by what sort of work you were involved in. Folks working in legal services, or in access-to-information/privacy areas were least likely to say that layers of approval were burdensome, while those working in procurement, real property management, or communications were most likely to say it was a problem. Kind of makes sense. If you're not the final word on something, then having a lot of additional middle managers can be "too many", because they will all have to sign off or insist on being consulted. Of course, I have no idea how middle-management-heavy those different kinds of employees are, just that they don't seem to be equally as bugged by it.
All of this just goes to say that there are a variety of perspectives on the matter to be had, with some folks more likely to perceive a glut of middle managers, as a function of the consequences it has for them personally, and other folks puzzled as to why the first bunch see a problem.