This seems to be a controversy, which is this:
Sci fi military, is it going to be evolved and different or a retread of what we have now?
Certain things will always make sense, like that you must have hierarchy in military commands, and only one person ultimately in charge. I don’t think that can change, at least for humans. When people buck this particular nugget of wisdom, you end up with military disasters. Command by committee = Vietnam.
As for the actual composition, you would be hard pressed to find something alternate to an officer/nco/enlisted ranking structure. That’s been around for 1000s of years.
Romans | Modern
Without organization, you have a cluster of people who fight as individuals, and that’s not a military. Or, not an organized one.
The proposed changes stem from an idea that mankind will evolve. [Haven’t any evidence of this, so it’s unlikely.]
Absent some sort of coercive behavior, most people aren’t strongly motivated to fight. Thus, hierarchy.