The Gundam FIX Figuration line started as toys based on the CG arts featured in Katoki's Gundam FIX column from Newtype magazine, which was later compiled and released in art book form. As the original book featured nothing but Gundams, they couldn't really release non-Gundam toys in the line, thus a separate name for the Zeon designs, never mind the fact that the GFF line now features many designs that never appeared in the Gundam FIX book.