Ah but you conveniently forget that such requires a course that permits the stronger riders to eliminate the weaker ones.
The truth is that with a tough Worlds course, Cavendish finishes, if he finishes at all, 10-12 minutes behind the likes of a Gilbert or an Evans or a Contador or a Schleck, whereas Cancellara took fourth at this event in a bunch sprint.
This is the difference in quality and caliber of such riders and such courses, while I find that a World Championship course needs to award a racer of high caliber which requires a suitable course. This doesn't mean necessarily high mountains, or even desirably, just something that allows the really strong riders to express themselves over the merely fast ones.
And I can't understand, frankly, all the debate over this.
Having raced at a pretty high level and not being a sprinter, I understand the difference between winning frequently and the actual quality of one's engine. Because the difference between being fast and being strong, is tike the difference between meters and kilometers.