I want a damage meter!

[Seraphor]

I would much rather dev resource time go into literally anything else besides an in-game excel spreadsheet. ACT exists for the people that want it; as long as they keep it to themselves they can use it to their heart's content.

Except console players of course.

While the example above is probably a bit too indepth for a built in meter, I wouldn't be opposed to some kind of 'Battle Report' feature, that simply graded your performance at the very end of a duty after commendations had been made.
Something like Speed of Completion, Personal DPS/HPS, Enemies killed, etc. and simply gave you a 5 star rating in each field.
This at the very least would alert those who are playing badly to that fact, and some metric by which to measure improvement.
It would also give incentive to go beyond simply 'clearing the content'. Day 1 savage prog would probably see everyone getting 1/2 stars, but by week 3 when everyone's mastered it, you'll see 4s and maybe 5s.
Could even tie it to a very minor reward, something like +10% gil for each star.