The game already supports in-game DPS and Healing meters... How about allowing individual players to see their personal performance numbers in both PVE and PVP? This feature is already active in PVP arenas like Cracked Planetoid, but I would not mind seeing this implemented for PVE maps like STF's and Fleet actions.
Alteratively, give me some Addon infrastructure and I will make this and more.
Unfortunately, I think Cryptic rolled their own UI scripting language instead of using something like LUA, so they're worried about security if they open it up to us. It'd probably be easier to incorporate a LUA interpreter and rewrite the interface in it than it'd be to make their thing secure, and they'd want to do that for all four of their current projects if they did it for one. Same reason they don't let us edit Foundry code directly, but require we use the GUI, even though it would really allow us to do some fantastic things if we could edit those "exported" Foundry files and then re-import them.
I hope they find the time to give us this, though; it'd be awesome.