bad design is a deliberate act

That might seem a bit harsh but I believe that every aspect of a design comes into being as a result of decisions made by the designers, whether that is a decision to actively create or a decision to ignore aspects of the design.

For some reason the architect of this hospital stairwell decided to create an intimidating and unpleasant place. Why would someone do that?

It's a rhetorical question because I have heard enough of the typical answers to that sort of question. At the end of the day, for me, it comes down to a disregard (by some degree) for the people who will use the building/object/system by all those involved in the creation of the building/object/system.

It's just plain rude.