I remember as a child my mum dressing me in a top and bottom made out of the same fabric, which at the time, was totally normal. You often bought a top and skirt that matched. But those days are long gone. Nowadays, the only acceptable way to wear two pieces of a set at the same time is when its a suit. Everybody realises this (mostly) and you would be hard pressed to find a matching set these days outside of an op shop.
However, another type of over matching has come to my attention which is almost as bad and actually more obnoxious on the eye. And that is colour matching. For example, I recently observed a lady wearing black cropped pants and black platform heels with a bright orange top and matching bolero, orange hoop earrings, orange bangles and deep red lipstick. Colour overload! It was quite startling to look at.
I remember a time in my teens when I was really into bright colours and used to do the same - hot pink top, pink shoes, pink earrings AND hot pink eyeshadow?! Everything had to match. But I was 15 and could pull off looking like a candy store because I was... well 15. I now realise that less is more and have become so comfortable in my neutrals (black, gray, white, silver) that I have to make myself put on colour. From one extreme to another I suppose.
So I think the moral of the story is, there's nothing wrong with colour, but you know what they say, everything in moderation. At the very least, use a few different colours to break it up. Or risk looking like Paris Hilton.