Awarding individual achievements is fine. Having the entire fleet adopt just one ship's individual insignia is implicitly saying that one ship and crew are the only ones that matter.
Besides, it's fannish. It undermines the reality of the fictional world by superimposing our perception of the Enterprise
as the center of all things. It's shortsighted when fans assume that the characters within Star Trek
's universe would perceive and feel about things in the same way that Star Trek
And of course, as we now know, it was based on a misconception. That's the crux of it: The belief that the arrowhead was unique to the Enterprise
prior to TMP was simply wrong, as "Court-martial" proves. It was always meant to be fleetwide, and there's now plenty of canonical evidence affirming that it was in fleetwide use long before TOS. So there's no sense debating the legitimacy of an idea that we know is conclusively wrong.