I think you're still missing the point, with this statement. Cause you could also just as easily have said "The down side is that warlocks will be INCREDIBLY unpopular since they only get 1 to 2 spell slots per day!"
Same number of slots per rest. Same everything.
Depends on how often you have short rests.
If we're going by the 1 encounter per day (and rests at night = short rest) model, then our hypothetical warlock has 2 spell slots per day (+ 3 invocations) where as the wizard has 9 spells total (+2 spell levels returned).
On day one, they both cast two spells. The wizard has 7 spells, the warlock refreshes and has 2.
On day two, they both cast two spells. The wizard has 5 spells, the warlock refreshes and has 2.
On day three, they both cast two spells. The wizard has 3 spells left, the warlock refreshes and has 2.
On day four, they both cast two spells. The wizard has 1 spell left, the warlock refreshes and has 2.
On day five, they both cast their remaining spells. The wizard is reduced to cantrips, the warlock refreshes and has 2.
On day six, seven, and eight, the warlock casts two spells per day and gets them back. The wizard recovers 2 first or 1 second level spell. Going into the "final" eight battle, the wizard might have a single spell left, the warlock comes in at full strength.
See, under the normal rules, you're not going to short rest every 1-2 encounters. You'll probably get two short rests if you're lucky during 8 encounters. The warlock there refreshes and get 6 spells, no where near the wizard's 9. But every day the warlock gets to short rest that the wizard doesn't get to long rest, the warlock gets his juice back and wizard does not.
So if you know you're going to face a single encounter per short rest and not get long rests, why would you choose a wizard over a warlock?
Doesn't make sense at all. Very few things are impacted by this change. Not every creature is a mummy.
The mummy is an egregious example. The definition of CR is "An appropriately equipped and
well-rested party of four adventurers should be able to defeat a monster that has a challenge rating equal to its level without suffering any deaths." Emphasis mine. You are not giving your PCs a chance to be "well rested". Therefore, they can't handle the same types of challenges. The CR -2 keeps foes less deady (and thus doesn't require as much drain on their limited resources) or the double XP budget (and that is just a guestimate, I haven't crunched numbers) would show what kind of real challenge a foe would be when the PCs CAN'T retreat, heal up, and go back in.
Many classes already have mechanics to get resources back per short rest; applying more of them only starts to miss the point. What could make sense is instead that classes be able to adjust their prepared / memorized spells, to account for new situations, potentially. There's some argument to be made there. (Also some argument to be made for during normal short rests too.
Ie, it's reasonable to let someone adjust their spells prepared to deal with (curse, poison, disease, restorable things) over the course of time. It's also reasonable not to, since "spells known" folks have to cope without that freedom and not like there's really any recompense for that
Spellcasters want to cast spells. My example above was two spells per day (barring rituals and cantrips) to handle problems and attack foes. I sincerely doubt two spells between short rests is not "going nova", but giving classes a recovery mechanic (esp sorcerers, who get really hosed: less spells, both sorcery and spells recover only on long rests) allows them to breathe at bit, especially when those pesky monsters make their saves!
That's a ton of potential resources. Especially when you consider things like Life Channel Div. Why is it so necessary to make the game so much easier? It's already pretty darn easy (except for 1st level, randomly).
What about a dragonborn's breath weapon? They breathe fire once per day? Or bardic inspiration: "Hey guys, I can inspire you three times over the next two weeks!"
Yeah, not ever ability needs to double, but some of them might need a boost on uses, especially if they are a bread-and-butter ability that refreshes during a long rest; otherwise you will see most everyone just spamming basic attacks and cantrips.
Absolutely agree. I'm surprised you didn't make an argument for, say, one hit die per short rest.
There is a distinction to be made between resting for HP renewal and resting for ability renewal.
I'm actually NOT slow healing; the idea that a good night's rest recovers all wounds does limit certain playstyles. I can understand why people want to modify that.
However, if I'm a caster, I want to cast my spells. If I'm a barbarian, I want to rage. If I'm a bard, I want to use my inspiration dice. In a game where I can't recover those abilities easily, I'm loathe to use them and end up sticking to resources that can be renewed. Additionally, in normal rests I know that if things get too hot, I can retreat, regroup, and try again. In this mode, if things get too hot, I lose (either by going home empty handed or dying) and that leaves no room for error. If an encounter goes south, we don't say "Damn, that fight was harder than we expected; lets rest and regroup before we press on", we say "Damn, that fight was harder than we expected; let's quit and go back to town."
Call it a personal preference, but I don't like the latter.