Have you never seen an iPhone (or iPad) in gold? Actual Au and anodized gold aluminum look nothing alike. Not even remotely close. Anodized gold aluminum a subtle light coloring closer to Champagne. No one could ever mistake a gold anodized aluminum

Watch for an Edition.
To the OP Apple may offer this next year. Could be with about 64 SKUs they have enough on the table as of now. Could also be that the small frame and subtle color don't work that well on the wrist.