I get that they've made it non-transferrable to stop scalping, but some people just aren't interested in autographs. Besides, you could easily sell the thing he signs for you.
As to the limit on the number of autographs...I don't know why it is being done, since we're not told. Is it a ploy to drive the demand up? Some cynical plot by the reptilian overlords who have hidden the dinosaurs that mankind used to milk for oil? Or maybe Cullen doesn't want to, or can't (possibly for medical reasons) sit and sign things for hours on end? I don't know, and it's no use complaining about the fact that he'll only sign a limited amount of autographs. The method to obtaining said autograph is fair game, complain away, oh ye internets!
assembling a Neo-G1/TF:TM cast. Please PM if you have (or know of) the following at a reasonable price: Classics or Henkei Prowl, Astrotrain, Ramjet, Skywarp, Sunstreaker, Sideswipe, Blurr, Perceptor, GDO Wheelie and Springer, or 3rd Party Motobot Arcee, FP Springer, iGear Ratchet and Ironhide, City Commander (and/or Ultra Magnus), Starscream (deluxe) Coronation add-on, or Spike and Daniel in their Exo-Suits.