OP misunderstands the relevant meaning of...
simple - not ornate or luxurious; unadorned: a simple gown.
...and/or...
severe - rigidly restrained in style, taste, manner, etc.; simple, plain, or austere.
The fact that both these words have other meaning and connotations is beside the point. But it's worth noting that stark (which ultimately derives from strong) often simply means completely, or extremely...
stark naked
stark raving mad
etc., etc.
It can also replace adjectival forms such as complete (e.g. - "This is in stark contrast to that").