Designers donning all black outfits. Stereotype or colour conspiracy?

I live in East London. I see a lot of people who ‘do’ fashion stuff. I come across a lot of people who do, or who plan to, design clothes. And one thing I have noticed, no matter how much they tell us purple is the new black this season, for them black has never been, and will never be replaced by anything. I came across this photo of Chantal Thomass, Parisian designer, on a sunny day in almost May, head to toe, clad in all black. A vacuum of colour and pattern, come on Chantal, is this not just too much of a cliché? In fact many fashionista attended parties I have stumbled on accidentally have been much dominated by the same fascination with absence rather than presence of pigment. If fashion design, like any good design, is about pushing boundaries, creating something new and exciting and avoiding the obvious, then should one not practice what they preach?
Now, I wear a lot of black, in fact if I was allowed to call it a colour, it would be a favourite, but my relation to fashion is much more of a reactionary one. I do not give birth to the haute couture babies that propagate and morph into the wearable high street fashion. It is not my initial actions that fuel self imposed irrational imperatives to be on trend with these seasons shades. So, is it all just a sneaky way of making us buy more clothes? If the new black was always black, seasons could go by and no fashion updates would need to be purchased. Or maybe they simply only like colour as a concept rather than a reality. Either way, I’ve always said, I would never get my hair cut by someone with a mullet. And similarly, I aint buying colour from someone who doesn’t know how to make it look good.