If Black Metal is a style which was played ten years ago, or twenty years ago, and is now merely mimicked, then it's pretty dead.
If it's being mimicked, it is the same. So it's been dead all along?
To respond to your earlier statement, it is not "simplicity", but, rather, "the appearance of simplicity" which is prevalent (in some cases) in Black Metal.
I don't see any musical complexity whatsoever in Darkthrone, Burzum, Bathory, etc. As with most ambient music, any complexity comes about only in listening to (not
just hearing) the music. The complexity is in the reaction and the meaning, not the method. The method is an absolute dearth of frills - this is where black metal's magic lies. It means something without requiring an academic explanation for understanding that meaning. You're given a very basic template, and your mind (or soul, if you're inclined to believe in such a thing) is set free to roam. Any baroque components, even if hidden, would only serve as roadbumps.
It's also where the genre's pitfall lies. Simplicity is easy to replicate. It's almost impossible to replicate well.