When in combat at least, each character should only have access to their own inventory. Maybe also to anyone they are adjacent to -- would allow for the whole 'Oh no, the cleric is down, quick, Ranger, grab the scroll of healing from them' type situation. But it would greatly increase the strategic management of your party's inventory.

Maybe as part of a difficulty setting? Or better yet a toggle separate from difficulty itself (or allow 'custom' difficulties)

They allowed this in DOS2. But, yes, something that really shouldn't be allowed.

You can even change everyone's gear mid combat right now.

Yes this needs to be fixed. Another thing that is weird is that you can loot corpses and take almost no penalty for it during combat.

Yes, this is Larian's 'Magic Pockets' feature.

Isn't grabbing something out of a pocket a free action in 5e? I don't see the problem.

Not someone else's pocket, who might even be on the other side of the room.

true, kind of wonder when my characters are going to die from starvation, thirst, and if they already used the restroom in there pants....its a game with lack of realism, get over it.

Unless players can access your pockets in MP, this is one of those "issues" that has a built in solution, if it bothers you, don't do it. Changing armor should be a no no, changing equipped weapons as well, excepting weapon swapping, but the simplest solution to "I don't like that I can take stuff from other characters in my party" is to not do it. I seriously did not know you could eat food during combat, because it never occurred to me to try, just like I never thought of taking items from another character during combat., or taking a long rest after every fight. It's just things that were a non issue for me, because I didn't do it, or didn't know you could.

It's not realistic, but it's pretty down the line of things that bother me, frankly.
I wouldn't be AGAINST "fixing" this, but I can't really say I care much about it either.

Given what a mess the inventory management already is currently, the less the game gives me reasons to spend even more time browsing my bags and moving things from one place to another, the better.

And frankly I can hardly remember more than one or two circumstances where I actually found myself taking advantage of this.

I personally use this feature so i don't want to see it go away but i love your idea of adding a restriction either based on difficulty.

Ditto ^ t, I've been using it since the very start during my second playthrough, which is more of a speedrun test. When playing a squishy person, it's nice to use someone else as a pack mule, especially so I don't have to go back to camp just to retrieve stuff I want to sell. I haven't had the chance to try playing multiplayer, so I imagine inventory works the same as it does in Larian's other games. Personally, I would then want to see characters have more autonomy in the game if I couldn't access their inventory.

I certainly don't want this feature to go away, is it cheesy? yes.. but it eliminates the need to constantly adjust what everyone is carrying, which I found kind of annoying in DOS. Is it realistic, yes, but I just don't need that level of micromanagement. The characters never have to stop and go to the bathroom either, sometimes you just don't want that much realism.

Frankly if it wasn't (as usual) for the multiplayer mode I'd wonder why characters even need to have distinct inventories to begin with.

PoE 1/2 and Kingmaker had a very convenient "shared inventory" for anything that wasn't strictly equipped by a character.

It just seems to trivialize the difficulty. I almost never use healing spells on my cleric because eating some sausages heals for more. I just think it would add a level of strategy to have to think about who is carrying what as opposed to just having a huge practically unlimited nebulous pool of health.

I realize it's possible to just "not do it" but like adding an Ironman mode its nice to gave it enforced as a mechanic

Combat actions:

Use an Object
You normally interact with an object while doing something else, such as when you draw a sword as part of an attack. When an object requires your action for its use, you take the Use an Object action. This action is also useful when you want to interact with more than one object on your turn.

Some people allow using a healing potion as a Bonus Action but that a house rule, as written, using potions, scrolls, eating food, etc should be a full action.

Just think about it, you are looking in a pouch or pack to find X and then use it in like what, a second or you can still cast spell, attack, whatever?