Guys, imbalance on low levels IS ALREADY an issue, so I don't get why you are using it as argument against OP's proposal.
Try to do dungeons below lvl 30 with arcanist and compare it to a synced red mage, the red mage will do like 3-5x more damage!
Same as any decent tank outdamaging melee dps because they dont have an aoe yet. It is already terribly unbalanced yet I dont see the low arcanists or melees being kicked, the community isn't that cruel.
However I do see many people avoiding leveling roulettes because its just too boring, so it definitely could use an improvement.

I agree that the defensive/healing abilities and invulns are a mess to balance for sure,
so it could be solved by allowing full dps rotation and scaling it down, while disabling some of the overpowered defensive oGCDs.
The whole sync-down system below level 50 just needs some adjustments overall, it is not normal to murder everything so fast and yet be bored to death lol