I can tell you that much of "Middle Management" today falls under the category of "Bullshit Jobs" and "Leadership BS" (books have been published on both). It is mainly due to mindset and the way that company hierarchies are structured. "Management" is considered prestigious and hence is given more money then they are worth. Everybody wants to be a "Manager" in one form or another (there is something in the human psyche which wants to lord it over others whether needed or not).

The erroneous belief that if you have a team of 4-6 people you need somebody to "manage" them is ingrained in the industry. Thus the proliferation of management "levels" as axioms.

Ideally they should grow organically only as a need arises otherwise a single level between Strategic/Vision <-> Middle/Operational <-> Engineering/Production should suffice (think of them as concentric circles with Engineering at the core). In a organization with a such a structure true middle management exists and you will see them involved in everything since they are the conduit between the end-goal and the means of production.