As Trish said so well, this isn't about the nonstandard colors and patterns being ugly or less attractive, the breed Standard is written to mimic the look of the Serval...and Servals mainly come in a brown spotted tabby form with a few exceptions. And it is possible one of those rare exceptions is not represented in our Standard and it will be complicated to add it.
Trish also mentions our New Traits option to add colors. But actually, Trish, TICA will not look askance if we start to show some new colors or patterns now. We did make a decision about a year before our application to advance to hold off on asking to accept colorpoint (snow) after all to when we could utilize the New Traits program. I tend to suspect that it will be colorpoint that is asked to be added before marble is. After all, the snow Savannahs can claim to mimic a coloring we do see in the Serval, the white Serval.
What I am reading here is that pet owners are disturbed but they don't show their cats. The breed Standard is for showing primarily and hence also what good breeders aim for. That doesn't mean that a great Servally-looking cat can't be born in an unexpected color or pattern, just it can't then be shown as Savannah... possibly household pet though!
My very first Savannah is a gorgeous boy, but he does NOT fit our Standard in many ways even though he is a BST. Doesn't make him an ugly cat, I think he's really handsome but he just isn't a good Savannah in type. Still, he is responsible for me falling in love with the breed and becoming a breeder and rescuer and exhibitor.