Not going to quote exact lines, but here are my thoughts on subject matter so far:
@darthmorf, with all due respect, i think others already explained to you why "it wasn't intented" is a poor justification to remove feature 10 years after the fact. I do understand you weren't involved with this though. As for playtesting, here are my results. Or rather list of Accessories that firmly fell victim to this social slot curse:
— All emblems. Playing on Expert i used to carry class-related ones in spare slots just in case, but now i take them only in case of particularly hard Boss fights
— Star Veil. Yep. It was tied with Greedy Ring in my 1.3. character inventory, but now i can't swap Greedy Ring out, so Star Veil goes to the chest, never to be taken again
— Shining Stone. Accessory that allows you to retreat to safer spot and heal up. I simply don't use it anymore.
— could have added Frozen Turtleshell as well, but it gets new visible thinker in 1.4., so it's saved
@Sora_92 I will probably repeat myself, but i don't see why "invalidating vanity intention" should be a reason to search for overcomplicated solutions. Because again, 1.3. actually gave you an option to use Vanity slots as intended and swap accessories with "quick swap from inventory" mechanic, that, apparently, fell victim to some sort of playtesting as well. I kind of can see why it was changed — cycling accessories may have been regarded as counterintuitive. I, for example, never used it. But now we have nothing to fill this void.
Edit: By the way..... in another thread
@Leinfors told me that at some time in the past he tried to pitch an idea for a full-scale load-out swap system, that was disregarded due to complexity. What if i told you that it actually does exist in 1.4 due to an oversight, no less. There are these mannequins that now behave as container-like showcases for not only armor but accessories as well. Guess what — THEY ACCEPT INVISIBLE ACCESSORIES. Now increase number of accessory slots on mannequin from 5 to 7 to accomodate Expert and Master players, slap a right-click option on top of that and you have very convenient load-out swap system allowing player to not only adapt for situational changes (that's what quickswap we're discussing should be for), but to quickly change his entire class without hassle of going through chests.
@Kardfogu, i kind of disagree with implications of your take on inventory being the same for 5000+ items. Managing it is a nuisance, but not because of 40 items limit. Playing the game for many years i can identify several bottlenecks in inventory and storage management:
Poor load-up management
I.e. general subject of this thread. The issue manifests itself only in 1.4, as two mechanics that mitigated it were crippled.
Inventory sometimes (events and extensive digging) fills up more quickly than it should
Mitigated by Void Vault. Yep, you have to keep it clean, but i don't see a way to solve it.
Btw banners imo are a complete red herring. I recently needed only six chests to store all my unused ones from 1.3 world and the maximum requirement for 99 of each is eight chests. If i were to design it from scratch, however, i would probably tie them in with new Bestiary system by making some sort of currency (or rather killed mobs score, that is currently world specific, but maybe should be player specific instead) that you can craft respective banner with, instead of just getting it right into your inventory.
Hotbar behaviour
I never knew what "lock hotbar" is for, but recently found out that it merely prevents hotbar from being clicked outside of inventory. Frankly i don't see why it isn't a default behaviour, since there is very little utility in clicking on a thing already accessible with hotkeys. However, what "lock hotbar", despite of its name, doesn't do is it:
— doesn't prevent random items from getting there. They go right into it even if the rest of inventory is empty;
— doesn't allow, if turned off, to remove said items out with "quick stock" button, which in essence means that items on hotbar always behave like favourited.
Btw, i just checked and "random items" mentioned in first bullet actually behave randomly. Although not so "randomly" — it seems to me that whether the item will go into inventory or right to the hotbar depends on whether it can be used on mouse click. So weapon goes there first, while piece of armor doesn't, which is understandable. However hotbar also gets health potions that are now covered by H hotkey and even Fallen stars, because they also have this meaningless Use animation.
Counterintuitive sorting mechanic
To put it simply i have absolutely no idea what it does to items belonging to one group.
Possible unexpected issue related to 1.4 Piggy Bank overhaul
It's not a problem for me personally, but i've seen report that auto-stock to Piggy Bank (now you can store coins without actually opening it) messes up with how some players used it pre-1.4. Particular report noted that now it gets filled with stacks of wood and dirt because player in question kept some of it there just in case.
Edit: Absence of hotkeys for frequently used things
Not exactly related to inventory, but some additional hotkeys are asking to be implemented. Auto-buff was a great thing, we need more of it.
Complete absense of visual cues
That's the biggest one, as it greatly amplifies aforementioned and other problems. To explain what's going on i will now commit a blasphemy and say that yesterday i fired up my old Starbound save. And i see that many years after, devs and community should learn a thing or two from it.
So, on the left is Terraria. UI scaling is set to 100%, but i actually play windowed mode with 80%. I have to use for a time being, since Mac is not fully supported for now and my framerate is abysmal. On the right is Starbound. UI scaling is again 100%. As you can see, inventory grid in Starbound is smaller than Chest grid in Terraria. However, Starbound has these bulky item icons, more easily readable font (special issue for me due to 80% scaling) and coloured borders. I can tell you about the latter one in detail — i couldn't care less about "sort inventory" feature in Terraria, since it doesn't sort it the way i want anyway, yet i repeatedly click on this button just because it flashes with coloured background. I want this background to always be there though, as Terrarian inventory really tests limits of my sight in times. Now i don't know what those borders signify exactly in Starbound, yet it's not a big problem to figure out, since stuff like building blocks goes into another screen of inventory anyway, as if it were 4 separate themed Void bags avaliable in one click. And did i mention that you can move inventory to the side and continue doing whatever you were doing, as it also doesn't have auto-pause?
Don't get me wrong though, i think if Terraria UI and inventory were bad, they would have been scraped long before. It's actually good enough. But only on paper. In an unrelated thread i covered the idea that Terrarian UI greatly amplifies fast-pased nature of the game. Yet because of this UI-gameplay relationship aforementioned things become detriment. Terrarian UI (and by extension storage management), as it is, could work without much of a problem, if you imagine likes of it in Minecraft, Starbound, or hey — Terraria itself with auto-pause turned on. But Terraria as it is meant to be played is a game where you may have 1 IRL minute (or even less) to switch from building, fishing or other meditative activities to fighting hordes of mobs. And you better be prepared or have a way to prepare yourself quickly.