It's crazy to me that they could design PCT's combo system and got zero ideas of how to make healers' DPS more interesting.

Just giving healers a three hit combo with a job-specific finisher when completed would go a long way. You could have the AST/SCH finisher GCD be a small "use-it-or-lose-it" damage or crit buff while having WHM/SGE have a big damage finisher in the form of tidal wave or placing a temporary turret similar to rook that will attack for a bit before leaving.

All of this can be done in exactly two (2) buttons and would add a lot more flavor (such as bringing aero and stone back in WHM casts)