Staying out of this conversation between Laney and Wulf, but just coming in to say...there weren't nearly enough green ARCs. In fact, A'den is the only known green ARC, I believe. Man, that would've been sweet, a bunch of green ARCs with Fordo.
(Any conversation between Laney and I will be handled in private, for my part anyway.)
As doe the colour coding of ARCs, I think that has to do with the perceived expertise level of the ARCs. Like for example, in the real world only officers can fly a fighter jet. I think it was understood that by virtue of their skills and training all ARCs are automatically officers. A'den bucks the trend by choice, in honour of Kal.
However there are a number of all-white ARCs in the cartoons. I'm a little curious about them...