The system would be a nightmare, to properly get this "Colour" system to work it would need to have optimal DPS ranges for your item level or some formula using the base weapons attack and the job itself. At this point why aren't we just cutting out the middle man "Colours" in this instance and just give flat numbers, they don't lie and don't care if your colour blind.

Damage meters are not going to solve anyone problem, ever, at all. They are great for the people who use them and are great tools for them, but that's not going to give you any less bad DPS/Tanks/Heals it's only going to give people official tools to harass players. Stop relying on the duty finder to solve all your problems and you will find yourself with quality players, people who you have fought with time and time again. These people have expectations to live up too.

Random Duty finder Joe doesn't care about you or your colour coded DPS charts.