to preface, 2 and a half stash tabs are indefinitely occupied and totally filled by runes, various consumable, horde keys, tributes, etc. even halfway into a season you shouldnt really have to occupy more than 1 stash tab with these general (non equip) items.
now ill start with boss materials. first off ill quickly state that they dont have to drop in such massive proportions (requiring 12 to summon and a full stack/inventory space only effectively gives you 4 rotas worth). malignant hearts are a perfect example of how the rest should be, God only knows why they made the others different. everything should require 4 with 50 stack, or the stack rate should be increased to 200. one or the other.
next is the amount of time you have to spend on runs. i spent hours doing boss runs, did some other stuff for a while, and immediately had so many boss mats again. stacks upon stacks. i do appreciate the ratio of runs to ubers/2+ga drop rates but its just too much time spent. im sure whoever at the top wants the devs to sneakily use as many mobile tactics as possible to artificially increase game time but lets be real, spending like 50% reduced time inside boss arenas (with the drop rate of mythics and GA uniques being respectively increased) would be way more satisfying. not to mention, exquisite blood and living steel are STILL dropping in way higher numbers than their counterparts which heavily triggers my OCD. if you cant balance the drop rates at least give a free 1-1 conversion on one of the crafting benches so that we can balance it out ourselves.
bringing me to my second point, infernal hordes. they literally said this would be something rare, that is highly rewarding but only done once in a while. i tried to slim down on the number of these things in my stash and its not even possible. there’s literally nothing finite about this activity. the more i run, the more that end up in my stash. from the materials cache at the end of the runs themselves, and i get whispers completed while im in the hordes which gives me even more of these things. if you spend time on literally any other activity in the game, the number you get is just insane. the frequency of these should be in proportion to something like a divine orb drop on PoE (of course again with respectively increased rewards in terms of GA items and obducite). hordes would be amazing if it was simply this ‘once in a while’ big dopamine hit.
whats really sad about this is that nothing else in the game satisfies the “rare drop” or “rare activity” itch so you’re left craving it.
ultimately, bossing and hordes should be “reward” activities for playing the rest of the game. somewhere you go to unload what youve amassed and quickly get some almost guaranteed upgrades, not somewhere that you spend literally half your total playtime.
next point, and many will disagree with this but i also think legendary runes should be less common and they should add the upgrade system from d2 (3 of a lower rarity always converts into a specific higher rarity). its just better this way. im only 220-ish paragon and ive accumulated close to 10x of every legendary rune with dozens more magic/rare and i dont really care to engage with the “spend 3 for 15% chance of increased rarity”. getting rune drops doesnt even feel good in any capacity. its just boring and pointless, theres really nothing different about this system in contrast to S2 vampire powers except that it takes up an entire stash tab.
they also need to add charms and unique charms like gheeds fortune for even more cool loot chases and exciting, rare potential drops.
then of course the fact that common materials are lacking, while on the other hand you have thousands of everything else. gem frags are capped, no need to ever salvage a single piece of equipment, etc. forgotten souls worked nicely in d3… early on they were a bit scarce as you spent a lot, but then as upgrades became less common you could stockpile them and choose to dump them on reforging while hunting for ancients.
this sort of thing can EASILY be applied to all the legendary salvage materials. the blacksmiths cache (most people probably dont even know this exists) is a decent start, but the loot it drops is trash and the bottleneck of course is the common/rare materials rather than the legendary ones.
tl;dr less frequent boss runs/horde runs but with greater rewards, better rune systems, and balanced material quantities with meaningful ways to unload amassed materials. less mobile game stuff and more real game stuff.