Humans have some strange reactions to clutter; organizing it is one of the less common reactions! For many people, it isn’t the existence of clutter that’s the problem, but the way the clutter looks (especially in a small workspace). That’s why we do silly things like tidying paperwork into neat-yet-unsorted stacks.
Making the mess look better goes a long way to improve focus and morale, which in turn boosts productivity. So give each employee a couple of storage boxes and ask them to box up anything that isn’t being used, keeping a few decorative items on show if they want.
Is your workspace tidy? Come on, don’t lie.