The Ultima series was known for its attempts of immersion (in the singleplayer games you are supposed to play yourself), so things like a world simulation were

The Ultima series was known for its attempts of immersion (in the singleplayer games you are supposed to play yourself), so things like a world simulation were built into it as the games progressed (you want to bake bread - get flour, mix it with water, bake it in an oven, etc). This spilled over to the UI/UX design - so having a free form inventory meant it felt like you had a backpack.