I would like to see a mod that creates an inventory system similar to the witcher 1. I never liked the idea of carrying 300 pounds of equipment with you.
Maybe an option like in Fallout 3 to buy bags or sacks to wear to increase your carry capacity.

All 5 TES titles have pretty much been the same. You can carry everything in one (invisible) mega-sack, limited only by your encumbrance capacity. Although I do really miss the horse and cart from the early days.

I just realized there are knapsacks and sacks so my idea is fully possible. In witcher 1 you can only carry maximum 3-4 weapons at a time plus maybe 10-15 potions and there's room for a little more stuff, I would to see this implemented into the game.
I know why bethesda made it like this, to cater to all the 12 year old kids who would complain that they have to come back and forth to a cave to get all their epic items they earned.