The whole issues of Kinect and Move being platforms are certainly interesting ones and not as clear cut as either side is trying to assert here.

On one hand, both are clearly add-ons, you need a 360 or PS3 to use them so they both benefit from and limited by the existing userbase. On the other hand, Kinect and Move are far more their own platform than the balance board, eye toy, guitar hero guitars or any other add-on have been. They have all been designed with a fairly limited function and although in some cases had good support, they were never really general enough to be considered as a new platform. With Kinect especially, Microsoft has intentionally tried to market it as a new platform. They have offered the casual gamer the option of a Wii at $199 with or Kinect at $149 (or $299 if you don't already have a 360)  with a lineup of similarly themed games - it is hard to argue that the two are not in direct competition if you look at it purely from a consumer choice point of view.

In terms of our analysis and what clients will want to see, Kinect / Move-compatible PS3s and Wii represent 3 competing markets. If I have a new motion title in the planning stages I will want to know the relative size and strengths of each of those 3 markets as that will be my target audience. Of course, if I were designing a fitness title that could be balance-board compatible, I'd be interested in that market as well but that is a far more limited senario.

Personally, I think it is valid to compare Wii to Move to Kinect as they are competing platforms as far as publishers / developers are concerned and as consumers see them. Move and Kinect are far more general in terms of appeal and input configurations than a standard game peripheral which is designed to mimic a particular action or activity (playing the guitar etc). They are also supported (or will be over the next few years) by far greater libraries than a normal peripheral so are really more comparable to a new gaming system, although one that requires an existing console to play.