Surely giving them 1-2-3 combos isn't enough, they have too many buttons already. So to make them more interesting you would have to twist their skills a little bit. I don't play every healer so I can't give an opinion about all of them, but here's what I would do with the ones that I play:

Scholar

Energy Drain - Doesn't cost any Aetherflow. Instead it gives Aetherflow I, have 3 charges and 20 second cooldown.
Aetherflow - Restores 10% MP instead, costs 1 Aetherflow.

I basically swapped Energy Drain with Aetherflow. This would make you deal damage consistently without having to grief your party by spending all Aetherflow stacks in Energy Drain. That will be at the cost of a more inconsistent MP gain, and a more strategic use of your resources (but at least you're not spending every resource on damage).

White Mage

Stone and Glare are two separate GCDs instead of one being the upgrade of the other. Stone gives a stacking debuff to the targeted enemy that does nothing on it's own and can be stacked up to 5 times. Glare consumes this debuff and deals damage based on the amount of stacks. Dia also gives 1 stack per DoT tick. Using Glare on max stacks also speeds the Lily Gauge.