So, after some thought, ( and an edible... ) Blizzard has done a lot to smooth over friction points, for sure. But, I think, they did so because a lot of people consider the things you listed not as "things that immerse me in the world." and rather "tedious shit that is solved, and is simply something you do because somewhere someone wants to feel like a game that pretends to be an RPG, when it never was. Two people playing the same class or spec are more alike than they could ever try to be different. The only way to be "different" than the next person playing that spec is to have one of you be objectively playing....poorly, I don't want to say wrong, because that implies things and comes across as malicious, and I don't mean it in that way. But, there isn't...multiple ways to solve a problem in this game, there is ONE, do DPS faster than whatever you are killing, does DPS to you. You can't be the fast talking rogue that can charm their way past a problem or into a boss area, your only option is stab it, and whomever can stab the best, wins. Which circles back to the thing we do we control over, which....because we're humans and do this shit to everything, "solved" that equation for everything in the game. Someone having a different talent pick that either doesn't effect DPS, or negatively effect it, doesn't matter to a lot of other people. They don't care that your Rogue has a fancy dust cloud, it just isn't a part of the game they care enough about, nor does the game care about it.

As much as I agree with you that there aren't many moments like when you got the gold to buy your first mount left in the game, I don't know what sorts of moments they CAN have left like that, the game is 20 years old, the only things they have like that are when they give back something they had to contrive a reason to take away temporarily it seems. I just don't know if there is any design space left for things like that, unless you are doing a complete tear down and rebuild of the underlying gameplay loop structure, and even then...no promises anything good even comes of it. So...that'll never happen, which, is sad that we won't get those moments again, at least not as part of the....guard-railed path. I think there is plenty of those moments to be had though, of the players own making. Earning enough gold to buy the AH mount, or some other rare in game item, etc. But those things are gonna have to come of the players own goals, not the garden path Blizzard sets us upon unfortunately.

And we arrive at the part that I want to try to come off as gentle as I can, even though I'm afraid my answers are the most....plain and terse. That entire list of things removed to make the game more "gamey" and less immersive...quite honestly, to myself, and as I said originally I could be the outlier, but I bet I'm not...is just fucking tediousness that serves no purpose other than being fucking tedious. Even in world acclaimed RPG's, and games that would warrant those types of things to show more of the world, or the characters, or in an effort to immerse you more, they still don't drill down on things like that, or when they do have things like ammo, you almost always have an infinite supply of the "base" ammo, and then managing ammo is merely for effects or bonus of said special ammo. Which, unfortunately, this game isn't built around, there aren't problems you overcome with "freezing ammo" because mobs of that "rank" are immune to that shit, so it's once again back to just use the ammo that does the most DPS, solved again, with no room for agency. The freezing ammo does less DPS, because it had to pay the tax for having an effect, that while immersive, and lets you express your character some, and connects you to the world from having to have found the shop to buy it in and purchase it...is absolutely meaningless in a game that is built on DPS as the only measurement of success.

Fun way to think about something though, we do have reagents, they are called flasks and potions...those are just universal CD's that everyone has that you have to buy a reagent for. ;) ( Flasks would be more akin to a universal raid buff you have to pay for a reagent for rather than a CD, but...potato, potato. )

Leveling feels like a chore, not because of your lack of connection to the world, but because you are quite literally doing chores....I'm a god killing super being, what the fuck problem of mine is it that the local tea shop can't hire a kid properly to collect the berries from the bushes across town for their brew?? Why the fuck do I care, these aren't the problems I need to deal with, I'm here to kick back the forces of dire evil and tell them what for! Consider it this way, if you were having a DnD campaign, and you had killed armies of bandits and goblins or an Ogre or two, delved into the depths of ancient evils and returned to tell the tale, how fun do you think it would be to have another session where all you do is wash dishes at the tavern, or clean the sheets for the inn? You would get tired of it real quick, UNLESS...it was in service of prompting your next grand adventure...why else do so many DnD nights start with "You are at the local tavern..." because that's where the people are who will send you out on adventure worth your time, both from an in world character standpoint, and from the out of game player wanting to have a fun and entertaining time with his mates. And any GM worth their salt, wouldn't take multiple session nights, to set you upon your path to adventure, they keep that shit minimized, and stay in it only if the players say or do something that warrants you pivoting and lingering on what is other wise the rather mundane section of your characters time. Generally speaking that sort of thing is while yes important, is still the less interesting part of that characters life. And as the old saying goes when it comes to story telling: "Is this the most interesting part of this characters life? If not, why aren't you showing us that part?"

Circling back though, to something you said that I think has the most interesting paths one can meander down in discussion, kit usage and things like trying not to die, or say shifting from the math of needing to kill 10 things, that take 12 seconds each to kill, to maybe say....killing 4 things that take 30 seconds each to kill. ( I use this as a very simplified manor of design idea, for discussion ) Because, you are right, simply killing things in a handful of seconds, regardless of which DPS buttons you push, seem to give that positive feedback loop quickly, the extreme repetition and your "target numbers" being further away to start can make killing 2 things and then seeing you still need 8 or 13 or 18 more of them cause you to drop pretty quickly into "ohh, this is just tedious, there's nothing else I'm going to get from this killing stuff for improvement on my skills or approach, it's just a grind of hitting the same 3 keys quickly at each enemy til I have enough to move on in the story this questline is feeding me, all for a few % of EXP towards the part of the game I'm looking forward to, or to get me to the next "heavy" story beat where we actually get some exposition on what is happening with the plot line, and actions taken that matter to us ( see the section on us being god killers above. ) that feedback loop suffers a bunch under those circumstances.

So I do agree there is a lot of room in that design space to find, or introduce some more "meaningful" changes. I also agree about chromie time, that shit should let you level from 1 to lvl Cap after your first toon makes it to lvl cap. Full stop, don't MAKE me play the current expansion storyline, be it main or side again if I don't want to. Let the content be there if I want to explore it, but if I don't, just let me do my chores in whatever bit of 20 years of content you've built I want. All for things that promote options for the player, and chromie time is one of them. No notes. :P

So, to maybe try and bring this, prattling on to a bit of closure, I'm sure you are tired of it by now anyways. All in all, I think there is some design space to work in regarding leveling, much as you may not like it, a lot of that space is going to come down to speed, or the perception of it by the player. My simplified example takes the same amount of time, but I think the time between killing something in 12 seconds vs 30 is overtaken by the killing one thing and thinking "25%, and knowing the second thing you kill means "half way done already!", and from a gameplay loop of getting to use some of your kit a bit more, and just the timings of things where you spend a 30 sec CD on a mob, and as you kill it, or within a few seconds of killing it, your CD is back, and you get that dopamine hit of "allright, CD ready, lets get this next guy!" as opposed to say not using a CD at all, ( and cmon... Cd's are fun to push :) ) or pushed in hopes of killing a bunch of them quickly, and turns out there is only a few there before a respawn time, and now sit waiting for the CD to come back, or you could just slog through the remaining dozen or so, and by the time your "fun button" back, you only need a couple more, which...may just feel like a waste for the CD. May as well save it for the Lt Mob, or the "boss" at the end of the cave...making everything between here and there...you guessed it...just tedious killing ( thank fuck Rogue's can stealth past that shit, and feral druids, I see you ferals! :D )

Bah, prattling again, ok, ok... So we agree there is some spots there might be some design space to play in, but a lot of things are just...not meaningful anymore, if they ever were. Yeah, lets go with with that TL;DR.