Divisions Starfleet should have

[BillJ]

Link to an article with an explanation of the color coding of the uniform jerseys on a US aircraft carrier.

Very cool link!

 

[Arpy]

No marines. No standing armies. Any standing military will want to engage in conflict, directly or indirectly, to justify its existence. This is what humanity has come to understand in the future, and why Starfleet is not a military organization. Everyone in Starfleet serves some civilian job duty and could easily transition to a non-Starfleet business or organization. They get double the training in the offensive/defensive arts to take up when in the statistically rare instances (adult) diplomacy breaks down or alien contact goes awry – for only as long as it takes to establish a diplomatic resolution. They are the fully actualized citizen soldiers of Utopia.

Interstellar nations that maintain standing militaries, regardless how noble their words or superficially well-meaning their people, invariably become captured and governed by their military-industrial complexes, the personal political interests of their leaders, and the fundamental bored, frightened, and culpable vacuousness at the center of their national and individual souls.

 

[CorporalCaptain]

They are the fully actualized citizen soldiers of Utopia.

The word utopia means "no place." It's the name of an imaginary place that's too ideal and too idyllic to be real, to exist.

We're therefore free to imagine perfect conditions.

We can therefore imagine that the soldiers in the standing armies of utopia are not subject to temptations that you describe. Rather, any Starfleet Marines or Federation ground troops understand that their role is to defend the Federation when called upon, to train at all other times, and to be content with that. Their glory is not to conquer, but to serve.

This is no more implausible than utopia to begin with.