I wouldn't pit TKD as a total style against much on the street. But I would beg to differ with you on the usefulness of its component kicks for causing real damage.
Here's a short (3 sec) clip of an out of shape duffer for reference.
http://www.megaupload.com/?d=5JNNS9D4
(not nearly as spectacular as the initial poster's clips but for more 'streetable' with running shoes and jeans)
I should have some footage of the same trick with basic roundhouses. It's a cheap parlor trick and no real accomplishment but the point is that there is some decent power behind them despite a showy factor or sport type chambering of the kicks.