It’d be useful and interesting if backpacks/purses/rucksacks etc, when placed on the ground, act like temporary storage devices. Ie, if you drop items onto the same tile as a backpack, it will drop items into the backpack.
When you Examine the tile it would ask if you want to get things out of the backpack. If you say no, you can pick up the backpack. If you pick up the backpack it will automatically add whatever was inside the backpack to your inventory.
This would let you organize stuff to some degree, and quickly pick up groupings of items.
In an ideal world these items would remain in the backpack (but still be accessible from the inventory, just tagged as in a container), so that when the backpack is removed it would automatically take the items it was carrying along with it. This wouldn’t change the way volume or weight worked, it would merely make moving items to and from your inventory en masse more efficient. It would be nice to be able to store your long-range gear (such as bedroll, some rudimentary cooking and crafting supplies, some water, and medicine) in a backpack for when you want to take a long overnight trip, and be able to just take it off when you’re back at your shelter, without the hassle of managing inventory.