I have a problem with the cleric, and that problem is that they’re not the monk or warlock.
I like druid casting like a wizard; they’re similar archetypes and should cast alike.
I’d want the cleric to do the same thing but for tbe warlock… except that warlock casting equals spammable cure light wounds equals infinite health. No fun.
One idea is to move healing to a paladin-like lay-on-hands pool. It’s a good idea; I’m not sure I’m there yet,
I have another fix. I’m not sure I like it yet. Neither am I certain I don’t.
In theory, the cleric’s Raise Dead line has a similar problem to what I’m describing with short rest heals; on a campaign scale the ability to daily raise the dead feels too cheap, so a cost is imposed. Dying costs 5000 gp.
What if getting injured cost gp, too? On a literal level, it does; potions of healing cost 50gp and are what you use if you lack a cleric. But what if we alter the text on healing spells to enforce that?
Then we’d be in a 4e-ish paradigm, but allowing the cleric to cast all day would be fine.
When a character is healed, someone’s gotta pay for it. Specifically, each time a character is healed via a magical effect, healer or healed (healed designates) accrue Debt Points equal to 1/10th healed points, rounded up.
A character running a balance of debt points cannot gain levels or long rest. And is being a jerk; don’t accrue infinite debt points, even though The System doesn’t actually enforce this. Bad juju.
Debt points can be bought off by spending 50gp per debt point.
Different characters can expend this cash in different ways; carousing, drinking holy water, training and sacrificing at temples and similar gp sinks all seem like reasonable approaches. In particular, if the debt is viewed as owed the power source providing the healing:
Clerical and palindrical require sacrifice at an appropriate temple or shrine. Certain deities might accept “virtual treasure”, monster carcasses, deeds, fulfillment of quest goals, other services.
Druids and rangers are similar.
Bardic debt is probably discharged via carousing, training the next generation and performing gratis.
You could even do this piecemeal; warlock-style clerical healing imposes Debt while slot-limited druids and bards don’t.
Regen and shapechanging are both dodges around this accounting scheme. Deal.