Lower Tier Class Balance
This is honestly a short answer, and mostly because trying to explain how difficult it is to balance content is very difficult to do, to people who haven't tried to do it. Lower tier classes cannot be buffed, due to the amount of time to re-balance for their increase in power, and the lack of available testers to provide accurate data, makes it impossible to justify even trying. This is especially true, when the majority of players do not make any attempt to maximize the classes they have, instead relying on the typical Warrior tanking, Paladin healing, most of the rest in auto attack melee. To illustrate this point, I stealth buffed a mid-Tier magician spell about a year ago to nuke as hard as the Idol of the Jailed, and it wasn't discovered for the 6 months it was Live. People just don't try that hard to make the most of what they have, when the next level requires all that min/maxing to happen all over again. I understand why, I didn't either.
I know neither one of these answers is what some people are looking for, but sometimes neither is the content that EZ provides. People will come and go, that's not new, and not something we're actively trying to mitigate through concessionary changes to earlier Tiers.
Would it be possible to add DPS balance to High tier content? Things like an epic aug on the lower dps classes (bard, ranger etc.) effect that adds some damage to bring them closer (but not above) rogue damage. I believe this was done somewhat recently with Monk and Zerk?
You could start it at 10/11/12 whatever works for easier development.