I agree with everything AnotherPerson says about Lucid Dreaming and Assize.
With the role that Lilies and Afflatus spells have in WHM healing, I'd suggest the following replacement for Freecure:
1) Lilies and Afflatus Solace become available at level 30. Cure II is delayed until level 40 and its cost is increased to 1200 MP. Medica II has its cost increased to 1600 MP.
2) Casting Stone/Glare/Holy grants two seconds of progression towards the next Lily.
3) Each Aero/Dia tick has a 15% chance of granting a Blooming Lily buff for 30 seconds. When Afflatus Solace or Afflatus Rapture is cast while under the effect of a Blooming Lily, a 100 (Solace) / 50 (Rapture) potency regen is applies to the target(s) for twelve seconds. Blooming Lily stacks up to two times.
4) Casting Afflatus Misery grants a stack of Blooming Lily.
5) When one of your regens (Regen, Asylum, Medica II, Blooming Lily hot) crits, your next Stone/Glare/Holy has its potency increased by 10%, stacking up to three times.
6) WHM HP restored per potency is reduced by 15%.
Rationale:
1) Freecure is a relic of when Cure and Cure II were a large part of the WHM's healing kit. Lilies have since replaced them, so it makes sense to grant access to Lilies earlier and replace Freecure with something that enhances them. Given the increased reliance on Afflatus heals that I have in mind, Cure II and Medica II will be last resort heals, so their costs are increased. Cure and Medica are left at their current costs for a low MP, low healing option.
2) Dealing damage grants additional healing resources. Greater uptime grants more free healing. This production accelerates the current 1 Lily per 30 secs.
3) Dot ticks grant a ~55% increase in healing output from Lily heals. Keeping high dot uptime will reduce the amount of healing that is necessary. The 15% proc chance means that there is an 80% chance of getting at least one Blooming Lily per 30 secs. This increases to 96% chance on two targets. Each 30 secs of dot will produce an average of 1.5 Blooming Lilies. While it's not absolutely certain, there is a very high chance that Blooming Lily will be available for every Lily that a WHM needs if they keep their dot active. A non-overlapping hot will require that the healer plan in advance so as to not overlap and waste ticks.
4) A free Blooming Lily ensures that at least one Afflatus spell can be assumed to have an extra hot.
5) Skilled healers will rely heavily on their hots due to their GCD efficiency. This grants an additional damage reward to those players. Buff stacks multiple times in case multiple coinciding ticks crit. All stacks are consumed on next Stone/Glare.
6) Dropping healing across the board keeps WHM's healing output consistent after buffing Lilies.
Optimal gameplay:
Apply dot to two targets if possible to fish for Blooming Lilies. Spam Stone/Glare/Holy to accelerate Lily CD.
1) Use oGCDs to heal.
2) Use Lilies to heal anything remaining, making sure to spread them out to maximize Blooming Lily ticks when possible. Use Regen for single targets if Lilies are needed for raidwide healing.
3) Cure II and Medica II are used next, though their high MP cost makes it prohibitively expensive to use excessively.
4) Cure and Medica are still bottom of the barrel.
This matches the current priority system, however skilled healers will increase how much healing can be done with step 2 and an overreliance on step 3 will drain MP fast.
Based on my cohealer's performance last tier (full oranges), a good WHM can maintain roughly 15-18 CPM on Glare in a savage fight, including forced downtime. That'll generate an additional Lily every minute. One minute of dot uptime will generate an average of three Blooming Lilies per minute, lining up nicely with Lily production.
Edit: I'd prefer to add some more damage options, too, but that goes beyond the scope of fixing Freecure.