I've heard a different theory... Well, I didn't read the article (no time, gotta catch up), so rectify me if I'm wrong here... But Rossi started doing this when he started cross-training on dirt bikes.... You ride dirt track corners with a foot out (equivalent to knee down for dirt), and me and my co-workers thinks it's just a habit which formed, and he carried it to the street.... THey got comfortable doing it on the dirt, and ended up applying it on the street....
With that said, there is no reason to use it on the street, as other said, you shouldn't be going that fast on the street.... And if you do it going slower people will give you a hard time for being a poser and such... But do it if you want..
