Er, yes? Other jobs could be balanced compared to COR, but do you understand that that isn't even what I was suggesting? You don't need to adjust the classes OR the content; you can just adjust the objectives.
Balancing other jobs to COR essentially turns them into COR. If the objectives are to deal x amount of melee/ranged damage, y amount of physical/magical damage and z amount of buffs/debuffs then you'd have to add these abilities to other jobs on the scale that COR has them.
Not sure about the consensus, but I'd prefer that the content not be handicapped according to what job I prefer playing. There was already enough elitist attitude in MMOs regarding personal performance to the point where I'd rather the content be designed to be challenging and enjoyable for all classes rather than force some sort of accountability through a rating system. I only see this leading to the elitist 'Your DPS must be this tall to ride' scenario that plagued upper level content. Slippery slope is slippery.
As for tracking progress "not working well," that's just plainly untrue. Many games track progress toward objectives--even MMOs, and it works well.
If progress is tracked and there is an indicator that you'd satisfied all requirements for full experience gain, why continue? If you know that nothing you do beyond a certain point would increase your reward be it exp, conquest points or a chance at spoils, you're staring the reason people went AFK right in the face.