Excellent question!
Those that are trying to "breed the color out" are working to preserving a historical breed. The "cream gene" is a recessive trait in chicken. The gene dilutes the gold pigments on the bird making its color what is called lemon, citron, or cream. This cream gene was discovered during the creation of the Legbar and the "Cream" Legbar was the first variety of chicken in the world to receive a written standard for Cream Plumage. Dozens of breeds have a crele variety that make the adorable flower looking birds with their salmon breast, but the Legbar is unique in that it is a Cream based wild type bird with salmon breast and barring. So were are preserving something unique for future generation to enjoy. Additionally by standardizing the breed it can be submitted for breed recognition by the American Poultry Association where as it currently has not breed status in with the APA and won't ever be recognized if not standardized. The flower like birds with gold neck are in no danger of becoming extinct. The Cream color how even is much more difficult to maintain in a flock since it is recessive so it must be actively selected for or else it will disappear.