I mean obviously having 4x times the inventory space would probably be just around the same as having stacks (more or less, probably better in most cases and you could use it for whatever items you want) without all the UX issues that stacks create, but i'm guessing devs are against this idea since this way they can't control what can and what cannot be carried in big amounts (limiting it to materials and not finished products) so you can carry around shit-ton of materials but can't fully loot 5 players without putting on some tsacks and a merchant.
Tbh I'd prefer more inventory space, but since devs are usually pretty much completely against removing stuff they added I'd like for stacks to be at least "fixed" for all the use cases mentioned in the OP and perhaps expanded to more items (because they won't give us 4x times the inventory, this is jorbtar we are talking about here, I'm taking what i can get)