Black is a colour that seems to be in fashion now, especially amongst women. It is not unusual to find women setting out to work dressed entirely in black, something I find odd.
Not that black is a bad colour. Black is sophisticated, smart but it is an evening colour. Black in daytime is only for mourning, which implies that it should be used with a degree of sobriety. No one should mistake someone in mourning for someone heading out to a smart evening party.
Dark colours, navy or grey, are acceptable if one likes darker hues but leave black for the evening. Little black cocktail dresses are best left for cocktails.