Notre Dame has never tried to coordinate colors in the stadium, as far as I know. They can't even settle on a primary color (Blue? Green? Gold?). Why start now?
I, for one, believe this is driven largely by the bookstore. They sell more stuff that way.
Back in the Willingham years he actually tried to encourage people to wear green, and to make "The Shirt" - which most students wear, especially back then, making the student section, at least, one color - consistently green instead of its usual blue or earthy tones.
That got torpedoed when someone realized that if they made The Shirt the same color every year, people would stop buying a new one every year. I think as a compromise they agreed to make The Shirt in multiple sizes, after 20 years of it only being available in a baggy mens large. Most women I know, and smaller guys like myself, were grateful for that, at least. Small blessings.