The reason why they're not cool is the same for any bling part, they're essentially something visual, designed to draw attention on the basis that they're expensive, distinctive, or purely trading on a "name".
No different to modern day wearing of Burberry, sovereign rings, and really heavy gold jewelry.
And argue however you like, but however you cut it, that certainly ain't cool. It may be a lot of things, including desirable for some, but most certainly not universally cool, never has been, never will be.