Remathilis
Legend
I think one of the biggest problems is only four classes (fighter, monk, warlock and moon druid) have bread and butter abilities* tied to short rest. Cleric, other druids, bards, and wizards get benefits from them, but they are usually minor benefits compared to their major ability of spellcasting. But everyone benefits from a long rest.
Further, many players only take rests based on hp depletion, not resources. So if a group takes on two encounters but maintains the majority of their HP, they are less likely to short rest, even if they have expended short rest abilities. It is usually a mix of HP attrition and lack of sufficient spell support that forces a long rest. Especially when spells like Prayer of Healing (aka the 10 minute fake rest) or Healing Spirit could be used to replace a short rest for topping off health.
(I'm sure there are groups who are more diligent about short rests every so many encounters, but from what I have seen and read about, I don't think it was prevalent enough, ergo the rise of prof mid/day.)
Of course, this is all in addition to adventures where short rests aren't available. Specifically, adventures where time is of the essence or the PCs risk continuous assault by stopping. You can't take a short rest in a prison break or racing to stop a murderer.
Ideally, the best example of what a short rest ability should look like is Arcane Recovery. It recharges a few spell levels worth of spells once per day during a short rest. If you don't get it, you're really not hurting about it, but if you can get in a rest, it's pure upside. More classes should have features where you have X per day, but you can recover one from a short rest. (A good example would be sorcerers who recover a few spell points on a SR). In the warlock's case, giving them a recoverable spell slot that they can use to fuel Mystic Arcanum spells in addition to the half-caster would be a good idea. Something that if they can't short rest doesn't deprive them of assumed power, but if they do can give them a one time boost.
* That is to say, something that actually affects their play style. A moon druid is a weaker land druid without WS, fighters and warlocks can't nova, and monks are just weaker fighters without their special abilities. They can be played, but the loss is louder than a cleric without channel divinity or a bard without inspiration.
Further, many players only take rests based on hp depletion, not resources. So if a group takes on two encounters but maintains the majority of their HP, they are less likely to short rest, even if they have expended short rest abilities. It is usually a mix of HP attrition and lack of sufficient spell support that forces a long rest. Especially when spells like Prayer of Healing (aka the 10 minute fake rest) or Healing Spirit could be used to replace a short rest for topping off health.
(I'm sure there are groups who are more diligent about short rests every so many encounters, but from what I have seen and read about, I don't think it was prevalent enough, ergo the rise of prof mid/day.)
Of course, this is all in addition to adventures where short rests aren't available. Specifically, adventures where time is of the essence or the PCs risk continuous assault by stopping. You can't take a short rest in a prison break or racing to stop a murderer.
Ideally, the best example of what a short rest ability should look like is Arcane Recovery. It recharges a few spell levels worth of spells once per day during a short rest. If you don't get it, you're really not hurting about it, but if you can get in a rest, it's pure upside. More classes should have features where you have X per day, but you can recover one from a short rest. (A good example would be sorcerers who recover a few spell points on a SR). In the warlock's case, giving them a recoverable spell slot that they can use to fuel Mystic Arcanum spells in addition to the half-caster would be a good idea. Something that if they can't short rest doesn't deprive them of assumed power, but if they do can give them a one time boost.
* That is to say, something that actually affects their play style. A moon druid is a weaker land druid without WS, fighters and warlocks can't nova, and monks are just weaker fighters without their special abilities. They can be played, but the loss is louder than a cleric without channel divinity or a bard without inspiration.