DPS display could easily be solved with a system already in game.

[Cynfael]

I honestly don't really need to know if I'm top dps or bottom, just if I'm improving over my own past numbers. Plus players generally talk about averages all over, you can look online to see if what you're scoring is decent.

I think the context of your specific group and duty experience is too important to omit. Your DPS potential, especially your DPS ceiling, is impacted significantly by the performance of your group (is there a NIN putting up TA? A BRD singing Foe's for casters/Paeon for the TP-starved? Selene buffing the BLM? A party member trying to give you the hug of death by chasing you around with a deadly mechanic?), and comparing your performance with that of similar Jobs in your party is important for understanding how well you are doing given your circumstances.