Have you ever actually FC’d a fleet or been in a fleet fight? There’s literally zero use for something like that. The only person that needs to even look at the positioning of the ships in the fight is the person or people giving orders, which is generally the FC and rarely more than 5 people in the same fight.
The actual line members can pretty much fly their ships through the overview, at least if the FC is doing their job right.
If any line member does actually need to look at the fight it’ll be in relation to their own ship because the FC said something like burn in X direction for Y distance.
The level of information or kind of precision you’re talking about is pretty useless and it would be a waste of time for CCP to try to implement something like this. Even if CCP did implement this, and even if some people did use it, the actual benefit would be minimal to non-existent.
I recommend going out and FCing some fights before jumping up with suggestions on features to improve this. I think if you asked most FCs what they’d want to improve the FCing experience they’d ask for more commands in the UI or something similar.