Very interesting experiment.
I, for one, always felt that game designers don't do enough to facilitate better team play. I have tons of "public" and "private" server experience from playing BF/Project Reality and Arma2/3.
But now that I've become a novice game designer myself, it is great to come back to this issue to look at it from game dev's perspective.
First thing that is important is a clear & simple representation of Command Chain. Not just roles, but the whole chain. In the heat of battle it is of utmost importance to be able to see at a glance who is responsible for commanding what units.
As in your example, having multiple Officer players lead to Line Infantrymen players being confused as to who to listen to/follow. One person should command a certain set of units. If he dies, there should be a person next in line who is automatically (or semi-auto) is assigned to act as a new commander.
Having several layers in the command chain obviously complicates things, but this kind of stuff can be automated.
Second, game UI should support giving orders without having to use the voice comms. Either by creating text-based hints, visual hints like gestures, arrows or whatever. Maintaining comms discipline is a problem in itself and requires a separate discussion. But being able to issue orders without voice comms is a step in a direction of decreasing the amount of inappropriate noise and bad language.
Third, there needs to be an incentive for people to follow orders from other people. Either mechanical, based on points scoring or similar rewards, or a prior consent in a form of community-driven rules that everyone on a server accepts to follow before being permitted to participate. Failure to comply, obviously, should be penalized, in accordance with the method of rewarding (if mechanical)/severity of rules (if consensual). In a mechanical based system, for example, server should ideally be able to have different configurations for specific community needs.
Thank you for reminding me about this sort of play. I've left my Arma community few years ago and haven't played anything team-based ever since.