Offensive casters should always do more damage than offensive fighters. The balance in this is that casters wear cloth and can't take nearly so many hits as offensive fighters can. They are the true "glass cannons." They do a ton of damage, but they can't take the hits that we can when we draw aggro. It's just the way light fighters and cloth casters always work.
I have to disagree with this and here's why. I have yet to ever hear in any group the casters calling out of mana unless its a long and i mean long drawn out fight. Plus with the game mechanics as they are almost all the casters have multiple types of crowd control which removes much of their risk of getting face to face with a mob if they're smart. I do believe that maybe outside of the rogue that SOME of the caster classes should always do more burst damage than light fighters. But over the course of a couple of hour grind the higher dps offensive fighters should be close to your top dps casters. My thinking is that a psi and necro should not really be out dpsing a dragon monk or rogue as they have alot more utility available to them.
One thing we have to keep in mind while talking about balancing is the fact that we have yet to see full blown raid content or real dynamic raid events for that matter. Unless you were one of the few select guilds back in 2.5 or whatever stage it was we really have no idea what effect the current state of the classes will have on those events. I honestly think that when the time comes for real raids and epic events that alot of classes will come into their own.
Now im not by any means saying the classes are perfect and they are starting to get them fleshed out but Id like to see some real raid content to get a gauge the state of class balance. After all for most raid content and high level epic group battle is the goal and so far we have really sen small time content for leveling and gearing out.