Clothing- wearable inventories
About a year ago a mod was released for ME that allowed players to bind stuff (like hats, helmets , etc) to body features. Similar code has been used by the modding community to create baisc armor and apparel mods.
However these mods are still baisic in their use and if the game were to fully adopt a fleshed-out clothing system that would allow players to craft and wear everything from boots to coifs. This would also improve immersion greatly as well as each player can dress differently.
Each type of apparel can be given attributes that would help in a certain field, such as faster walking with boots, or decreased damage to armor, or just things like satchels and backpacks that, when equipped can allow the player to hold more in their inventories.