Today, I would like to highlight two of the design principles of Donald Norman, from his book “The Design of Everyday Things“: Visibility and allowances.
Visibility refers to the fact that things need to be visible or at least perceivable. If the state of the software changes, show it somehow. Allowances refer to the fact that a user interface must be visible. Dilbert explains it quite well in this cartoon: Black buttons on a black case make the product inevitably unusable. If something can be performed on a product, the user must see how to perform the action. The user must be guided unconsciously.
Unfortunately, these two principles are too often sacrified merely for beautiful design.