Dressing for an interview

How do we dress for an interview? These days it seems that a nice, black skirt is out of the question. When I go to an interview, I think of putting a skirt on but people say, “No.” Today, it’s mostly black pants and nice shirt. Do employers think something different when an interviewee wears something else?
Also, why should it matter what to wear when really skills should? I contemplate this question to ask why it matters what a person wears when really the skills should. Even though, it is a business ocassion to dress professionally and impress your interviewer by being professional and on time. I understand that but what about those that look down on you because of what you wear. Should it matter I ask? It shouldn’t in my opinion. Clothes are thread and they shouldn’t be the ones to make the person. They are just a physical impression, an image. If you are judged by the way you look, wouldn’t this be a stereotype?