I like how they show it right at the start of the series, letting you know this will be a regular occurrence.

My theory is that it made the writing too easy and was an escape out of half the challenges they face, so they stopped using that as a solution in the show.

Black uniform: You have fucked up, or you will fuck up, or you are being recruited to fuck shit up, and there's nothing you can do about it.

That's basically the same idea as what navies do on aircraft carrier decks: each role wears a different colour basically head-to-toe.

In this case, I think the colours should be more reserved for operational duties - command red, bridge orange, medic green, engineering purple, combat/security black, etc. and anyone else not in an operations role would wear a navy blue and their specific role could use insignia like atomicbocks commented in a sibling to this comment

In TOS they had a different emblem in the center of the patch that later became the combadge. In fact originally each ship was going to have a different patch, though you can only see this in like one episode. Though this image doesnt show it I have also seen a Red Cross used for the medical emblem.