My foes will surely give up and abandon their quest if they have no source of comic relief. I will not fly into a rage and kill a messenger who brings me bad news just to illustrate how evil I really am. Good messengers are hard to come by. That way, the citizens will be jaded in case the real thing ever comes along. I won't require high ranking female members of my organization to wear a stainless steel bustier.
Morale is better with a more casual dress code.
Similarly, outfits made entirely from black leather will be reserved for formal occasions. I will not employ devious schemes that involve the hero's party getting into my inner sanctum before the trap is sprung. I will not turn into a snake. It never helps. I will not grow a goatee.