I know the idea was proposed several times in the past and got no positive feedback but here I am with my own thoughts. Please read till the end ^_^
I would like the implementation of sacks made of any kind of cloth. They would be used to store a stockpile, same behaviour as a wheelbarrow, but with the difference that you can make another stock made of sacks for a maximum of 9-10. With this, one could save some space around his own base.
The idea is to use sacks not for everything but only for the following: carrots, beetroots, onions, turnip, lettuce, flowers, wool, peapod, cucumber, sand, skin (and its derivatives) and feathers (and some other little stuff?). Things like seeds would be useless as one can already store them in barrels.
I even thought to stock up in sacks things like tree seeds or pepper, but I don't think it would be easy to implement as there's no stockpile for them and, perhaps, even useless.
They could be carried around like one bucket (store in you're inventory but once loaded no longer) but you would need both hands to lift them.
Once stockpiled, you should not be able to load them again in a wheelbarrow or even in a sack again.
And for the aesthetics lovers, as the sacks should be made of cloth they will naturally have different colours as the material used. A one mono-colour per sack should be enough?
With this you have a less powerful tool to pile up things but more colourful and troublesome than a cart.