lichmaster
Hero
I really like this idea. In 3.5 this was implemented in the Trailblazer spinoff. Spells were classified as "rote", "restricted" or "ritual".Another approach that I would be tempted to adopt is moving all spell casters to a short rest refresh mechanic
IIRC rote spells were self or single target spells and all slots used for casting such spells were recovered via short rest, restricted spells were mostly AOE and only one could be recovered via short rest by expending a "heroic action" (similar to inspiration), while ritual spells (campaign wrecking spells like teleport, strong divinations etc) could only be recovered via long rest.
Any sweeping change/unification to the rest/recovery system will have impact on all classes though, I'm not sure this can be done without having to redesign every class from scratch.
That said I'm of a strong and growing opinion that in the long run (not so long probably), having consistent and unified underlying mechanics greatly helps and enhances 3pp support. Rest economy in particular can create annoying and pointless tension at the table. Specific, class based rules make the system easy to develop on only at the beginning, but then it becomes byzantine and full of unintended side effects