I think you also have to look at the time span between SDCC and CV. It is only about 3 weeks. Thus, I am sure the logistics of getting everything that they display from SoCal to Orlando and all the staff time out of the office is too much for such a short time span. For the other Celebrations and SDCC there has been 2 months or more between them.
Never mind the fact that LucasFilm took so damn long to announce exactly when CV would occur that to suddenly change an already full product pipeline for an exclusive would be too much interruption.
That hasn't seemed to stop every other SW licensee from attending CV and offering exclusives, including others from SoCal.