Perhaps because it won't fit in a C-17 or C-5. 35 foot span on the B- too big without taking the wings off, and that would be a major reassembly.
Thanks for stating the blindingly obvious sandiego. Of course the wings have to come off, just as the rotors have to come of a helicopter when that is airlifted also.
http://defensetech.org/2011/08/25/ou...home-in-a-c-5/