If I may answer both Sid and Zio at the same time: the use of fashion photographers has nothing to do with fashion; it has everything to do with the hope that a fashion photographer will understand the difference between artistic nudity/topless/semi-dressed that a simple tit'n'ass specialist might not.
It was exactly the reason why I had succes with calendars: I came from a fashion photography background and that gave the ability (or it was always there) to work with and understand women a little bit, particularly to understand femininity which is a whole lot different a thing from top-shelf magazines.
Fashion, per se, had nothing to do with it (Pirelli). It was all about attitude, and that wasn't fashion as it's understood. However, if you are willing to change your statements to 'fashion photographer biased', then I agree totally.
However, there's a caveat: many of the top fashion guys have, in my personal view, fallen flat on their faces with the Pirelli calendar; because you may have some good taste doesn't mean you can also satisfy a wider audience. It would be invidious to name names, but take a look at the latest collected sets that have been published - I have two different ones - and you will rapidly see that a zillion covers of Vogue doesn't stop you failing.
But hey, believe as the mood takes you, it's Christmas and the season for charity!