FireLance
Legend
I wonder what would be the gameplay effect of requiring the expenditure of Hit Dice to get the full effect of healing word and cure wounds. For example, healing word allows you to spend one Hit Die to regain 1d4 hit points per level of the spell slot expended. If you are out of Hit Dice, you only regain hit points equal to the spellcaster's ability score modifier. Similarly, cure wounds allows you to spend one Hit Die per level of the spell slot expended. If you are out of Hit Dice, you regain 1d4 hit points per level of the spell slot expended.Vaguely similar, but shorn of critical parts: Healing Surges vs Hit Dice
See, Healing Surges aren't just "this resource is for healing." They served an additional, vital function: Capping daily healing. Yes, there were a few ways to skirt around this limit a little bit, but those were always in short supply as well. Either they were daily powers (and thus effectively "this power grants an extra surge or two once a day"), or they were addressed by the Bag of Rats rule (no beating up a bag of rats to get infinite HP). Further, almost all healing other than the aforementioned daily healing abilities (like Clerics with the "Cure X Wounds" series) required healing surges to function--even healing potions did! This meant everyone, even a Slayer or some other (sub)class that didn't give two figs about daily powers, had a metaphorical "clock" running down until they had to rest. That 5e removed this is a really, really big difference; HD are a nicety added on top of the critical necessity for magical healing, while HS are the core of the healing system and magic can do little to stretch things any further than surges allow.
In this way, it is more resource-efficient if you spend Hit DIce during a short rest (even if you don't have a Constitution bonus, you won't need to use a spell slot). It might even encourage the PCs to take more short rests!