Interesting Nathan (and Howard.) In this discussion about Moodle versus Canvas, I might be a little off-base as to what you seek, Nathan.
I post two discussion topics from my Canvas course. Can you tell which one has groups and which one does not? Well, at least Moodle shows you. And Moodle does take it one step further that you can change the grouping by clicking on the icon showing you what is what.
So might you be suggesting that Moodle's approach makes it too easy to allow teachers to make mistakes? Are you saying that you would prefer that Moodle not show you which discussions are grouped or ungrouped, like Canvas does, and forces you to have to go deeper to avoid unintentional errors? Or are you simply saying that you prefer that changing grouped forums not be so easy?
Or, does your question have nothing to do with Canvas and is instead just a feature request for Moodle? I do like your coloration. I am not an "accessibility" expert, but somehow it seems that colored icons have become less common, maybe for accessibility reasons (that I don't understand.)