Lots of rpg style games have stashes where you can throw stuff you don’t need but don’t want to throw away either, and with the emphasis on realism and immersion that this game is going for I think it would be really cool if NPCs could steal your stuff if you left it somewhere they would find it.
I’m kind of surprised I haven’t seen this in a game before since it wouldn’t even be that hard to do. It could just be if an NPC’s travel route takes them within X distance of a container you put items in (or even just items you dropped), and if the item is worth more than X gold, and if there is no one else within X distance to witness them stealing then they’ll grab it.
Just that alone would make it more interesting to have to hide your stuff somewhere out of the way. You could also get a lot more detailed/complex with it by making it possible to lock or conceal/bury a container, add some NPC criteria for how moral or law-abiding they are that might make them less likely to steal stuff (e.g. it could mean the item has to be worth more gold for them to be willing to steal it), etc.
I see this as a little way to make inventory management more engaging, and would make the overall game a bit more immersive by making you just as susceptible to having your stuff stolen as the NPCs are to you stealing their stuff. It could also make for a funny quest where maybe a village has a skilled thief who will try to steal from you if you aren’t careful, and if he does then you can try and get him arrested by guards, try and steal your things back, hire mercenaries to beat him up/kill him, something like that.