Super happy about this update, little things wanna point out though and maybe it matters, maybe it doesn't.
Firstly, I think placeables like doors count as items for the sake of this thread/category and while it probably wasn't considered relevant, I think maybe the QOL change to allow auto-open/close of doors and tall gates when walked through might be something that would fit there.
On that same note, I think it would be great to have a similar quality of life balancing given to trap doors so that they can be auto-opened/closed when 'Player Characters' attempts to jump up or move down through them, and despite 1.4 being intended as the final content update, I think we'd be missing out if there wasn't a wider length alternative to trap-door similarly to how doors have the tall gate alternative since a two block wide vertical tunnel can be a tad difficult to maneuver into from moving horizontally, which is why I always opt for 3 block wide instead if possible. (Obviously themed trap doors and tall gates etc. would be great too, similar to what is available for doors, but that's not my main intention here, just a little side note.)
I know most people will be thinking a change like that just turns trap doors into another platform, and while I am looking for the functionality to be similar, it's more so about it functioning like actuated blocks in a floor/ceiling that enemies, npcs, projectiles etc. aren't going to just climb, jump, fly or fall through like platforms allow. A lot of players including me will often use platforms as a way to jump between floors, to be honest I hardly even turn them into stairs except for npcs or aesthetics, it even lets some light through, but having those platforms in place of an elevator means that enemies who get inside especially during a bloodmoon will just jump up through the platforms because everything is able to pass through a platform. What I propose allows Trap Doors to remain more like a proper floor or ceiling piece but extends their usability and gives players the option to have a more accurate/realistic roof crawlspace or basement which is also better secured, also giving early game players the option to create underground bunkers or *cough* vaults *cough* without as much of the struggle getting out and keeping them separate enough to want to use both Trap Doors like a manhole cover or bunker hatch and platforms as the ladder you use to climb up to it, without taking the extra time to rightclick open and closed your trap door if you want to get out quickly and safely without letting enemies in. Just as much reason and use as regular doors got.
Secondly, I think it would make sense for a lot of rarer item drop rates to be increased further in master mode than they are in expert mode, eg. normal = 0.1% drop chance, expert = 0.25% drop chance, master = 0.5% drop chance. While having new potential expert-only and master-only drops is certainly what I look forward to most, I think it's definitely a fair and also commonly used balance to make playing at an increased difficulty more rewarding and worthwhile, as well as cutting down on the time it takes slogging through enemy farming or world-gen exploring to find certain items that we might want or find helpful in progressing past certain point in our play-through, which on master mode takes long enough already due to enemies having increased health and damage. I mean I've died more than I ever have before in the new master difficulty which I would say likely makes manually farming less viable and afk farming even less so for a number of people, at least especially earlier on when players don't have the gear to be able to handle it. Furthermore, there are some pretty decent things in the game like the Slime Staff, which could prove especially helpful early on, especially as an upgrade to the finch staff (beginning to hate having a birds nest on my head) and especially since summoners hardly have any gear for their class at the start of the game even with 1.4; there's no summoner armor, Finch Staff, Slime Staff and a few whips are all I've been made aware of as of yet for early stuff. Even the rod of discord later down the line, which a lot of players might be really unlucky and unable to find potentially for the whole play-through, at least not without getting lucky or farming for it for a long time. Lemme tell you, my first Rod of Discord in a normal mode world for my first main character took me roughly 3 days of afk farming for most of those 3 days off and on and I wasn't happy about it.
(For the record, it took creating 15 large worlds in 1.4.0.3 to find 1 pyramid in one world, and 2 pyramids in a different world, just so I could get the items I wanted from them)
Lastly, I know this is more pre-1.4, but player Sensors could do with having an option for each of the 4 directions to expand usability and furthermore I think there should be Monster Sensors that also allow for the 4 directions as this can allow players to better organize their wiring contraptions and make use of the space available to them without having to regress back to pressure plates which basically anyone can accidentally trigger or switches which you have to manually find, get to and turn on/off when it suits, removing the possibility for enemies to trigger anything themselves. For example having a player sensor in the roof/ceiling that is pointed down to trigger something as you move upward or having a player sensor in a wall to the left or right so that as you run at a wall it can trigger something, perhaps you even just want a wall or trap to only turn on or off when an enemy is in range of it. While these scenarios can be worked around with the current existing upward facing player sensors, however there will be occasions where a lot of our space is already in use by other items or sensors or wiring, or where placing sensors might mess with the aesthetics and so we'd rather place them somewhere else and basically you either have to opt to not use them at all, or reconfigure your whole setup, potentially re-build your whole base or what have you, just so that your sensor fit's into it both spatially as well as aesthetically.