I dont know... Im more leaning towards fangpyre's reasoning.
A new trainee (who I just turned into a switcher, THANK YOU!) went out and bought a MBP even though when describing his needs he didnt need much more than the entry level macbook.
That might be it, oh its pretty, oh I WANT the best! then its oh... this is huge for a notebook.
Though That should also apply to the top of the line iMacs shouldnt it? and I dont see many f those being slod.
Or do people just prefer notebooks? I know I dont.