No backpack of whatever size would be big enough to take the amount of stuff we get. But a bigger backpack in reality would hinder in combat, so it would be less immersion for me to have one in game, except you could and should remove it before combat. Some carrying animals would be a nice idea but would make group movement even clumsier. So a magical carrying and delivery service seems to be the best solution, aka like it's now.
On the other hand no sane person ever would run and jump around with sharp and pointy weapons attached to the body without sheaths or covers. I would really appreciate if we got sheaths and carrying systems (belt, baldric or such) for weapons. Including quivers for arrow and bolts.
