I do feel that slowly, edition by edition, D&D is moving closer to it's recourse management being tied to it's round based action economy which I actually enjoy.

As a player, it's already pretty easy to play this way, before counting subclasses, the rogue has literally no abilities that are limited by anything but once per turn, and if you pick some fun narrative spells as warlock and rely on invocations and eldritch blast, you can be totally effective without any resource management. Both of these exclude hitpoints of course but that is a pretty reasonable resource for a combat focussed fantasy game.

You can play fighter or warlock. Dnd limits extreme power with spell slots and charges. Otherwise they'd have to nerf the upper power level. Can't have people casting fire storm every few minutes. It'd ruin balance AND ensure you had to cast that every time to deal with increased threats.

Yeah, I hate that DnD is such a resource management game too. (More so that is is the ONLY game my group will consider playing.)

I tend to horde any limited resource. TTRPG or video game.

Is this group of mooks big enough to justify using power/spell/item X? Is there a bigger group around the corner? Is this just a lieutenant or the BBEG? Oh, this guy is monologueing, he must be the BBEG. But does his fight have multiple phases? OR is he just a puppet and the real BBEG is waiting for us to blow all our abilities.

Doesn’t matter how narratively I’m engaged in the plot. I’ve got a tactically aware mind and these thoughts are always there.

I really like where D&D's at, since it has multiple classes at every point along the "at will" to "once per day" spectrum, so players can pick what they like. D&D 4e tried homogenizing everyone into having mostly "at will" powers and players (myself included) hated it.

Agreed about not liking that D&D sucks all the air out of the room, though.

Most abilities should be either "per round/turn" or "per encounter".

Abilities that are too powerful for that should either not exist or require significant preparation (enough for the opposition to have a chance to discover and interrupt it).

Abilities that fall in the second category should automatically come with a less powerful variant in the first category.

Maybe as a middle ground some player abilities could use the "roll for recharge" mechanic from powerful monster abilities.

If you like large power scales and epic stories I very much recommend Earthdawn.

NGL if you take out what's left of the resources in 5e you'll reduce the game to exclusively standing in front of the enemy taking turns hitting each other, instead of just mostly.

The truth is if you want a resourceless game you're gonna have to play a different system, and if you're gonna play a different system you're gonna have to run it. Luckily, it's very easy to get groups for new systems, because you just tell the 5e players it's D&D and they probably won't even notice the rules changed.

Guidance would also fit well.

Another system that does it well imo is Shadowrun. In 5th edition (never played the others) when you cast a spell you can take mental damage. If you cast the spell on a weak level you are fine but if you go full-out then you can KO yourself pretty quick. Especially if you roll bad on your damage resist roll.

5e is still balanced because of the opportunity cost. If you grab that 1 level in warlock, you'll never get the level 20 perks of your main class. If you pick up that 1 warlock level when you're around level 5 it means you're postponing your next main class power spike by a whole level. The rewards have to be somewhat worth taking because of what you're losing.

And to be fair, none of the official campaigns even play at level 20. It may sound OP doing that much damage at will but you're missing the context. Your enemies at level 20 are basically going to be literal gods. You're going to be playing a homebrewed campaign. Your DM has many tools available to make your level 20 cantrip balanced, not least of which is just scaling up the enemy HP.

PC Warlock (A): I finish my turn, open the door and take a short rest."

Me (GM): So you what, slump against the wall and take a nap?

PC Warlock (A): "Effectively."

Me (GM): "You can clearly see an armored bandit in the next room, along with three skeleton archers and another set at the far wall."

PC Warlock (A): "Can they reach me on this turn?"

Me (GM): "No?"

PC Warlock (A): "Can they hit me with a ranged attack, this turn?"

Me (GM): "Also no"

PC Warlock (A): "Short rest."

What's a good example of an item like that?

Same here, I'm always debating with myself:

"Should I use this? Should I save it for later? I'll save it."

Then I never use it...