Because he had some actual talent, 2) it was part of his stage act, 3) it stopped when the 70s did.
There is a difference between KISS, Black Sabbath, Alice Cooper, Bowie, and this mess.
Also, Bowie spent the last years of his life as a devoted family man. He did all that experimenting only to find in the end, that was the best kind of life to live.
You forgot Twisted Sister. What about Boy George? We can certainly say the same of effete artists over the ages who did great artistic things.
Is there a difference? The groups you mention certainly brings it mainstream and legitimizes it. I would not group KISS, Black Sabbath, Alice Cooper, Bowie, into the mentally healthy group of individuals we wish to emulate, yet their popularity encourages emulation. I would also suggest that while the groups you cite may be to your tastes or that they may have produced a catchy tune or two, they are hardly artists in any real sense of the word. They are merely part of a perverse pop culture whose work will be forgotten. Why do these alleged artists dress in this manner? Why can they not stand on talent alone? Perhaps they have none? Just like the lost souls in this article; to create your own person of real character and true talent is a difficult thing to do. It is much easier to superficially affect the facade and scream, “Look at me!” As C.S. Lewis would say, “Men without chests.”