My guess is that it helps the sales guy to get you to spend a bit more and thats it.
Picture the scene, we have this model at (what ever your original budget is) and then there is the 'prosumer' model which has XYZ extra features for only a little more of your cash, I guess its working if your buddies are talking about it.
It also gives the press something new to write about - "Top ten prosumer cameras", "Are you ready to go prosumer", "The prosumer revolution" - I could make this c5ap up all day, some days I DO !
Duane B