Eccentric? Hardly. Most of those people have similar styles and/or themes, sounds, or lyrics. It's all blah blah blah to me.
True eccentricity, in my opinion, is a product of utter obliviousness to the social norms and conventions of a given place, culture and time, combined with a certain inner brilliance. Any and all attempts to recreate what naturally occurs are easily detected as such (ahem, lady gaga). Oversize accessories, crazy hair or Kermit the frog outfits are completely unnecessary and only serve to undermine one's own presence.
I am tempted to say that it is usually the artists who are likely to be eccentric, but the people who are receiving this (for lack of a better word) label are anything but artistic. Lady Gaga's songs, albeit catchy, are completely vapid and contain no motivational message or relevance to anyone's life (except maybe her own, but I wouldn't know). It's not only Gaga, though. I mention her the most because she is the current "it" girl of the music business. The public seems to treat her as though she's some sort of never-before-seen godsend. I reckon they have forgotten about Gwen Stefani and Madonna, both of whom at least had the decency of singing songs which were more-or-less coherent.
Eccentricity usually accompanies brilliance, only because the brilliant are too immersed in an advanced state of mind to observe petty social "norms". I would place Michael in this category, because he was bloody brilliant and one of the most artistic people to have ever lived. He had that certain "something" which, honestly speaking, escapes description. It's art, and brilliance and passion and a certain sense of aloofness from that which is commonplace, somehow complimented by a deep awareness of that which surrounds us all. That's the best I can say to describe it.
Eccentricity, at least the way I see it, has nothing to do with "weirdness" or "strangeness". There are plenty of utterly strange people in this planet (like ill-qualified "journalists" and a district attorney who seem to be vindictively obsessed with a certain celebrity) who haven't an ounce of brilliance within their system.
Eccentricity, I think, is the physical expression of brilliance. It's something that pretty much can't be controlled or fabricated. In any case, none of the people you have named in your post have it, as far as I am concerned.
I conclude my post by stating that I have put my shiny two cents in. :3
