[bfgoodrich]

The Apple Watch oximeter functionality -- basically a pretty silly gimmick -- is explicitly marketed as “not intended for medical use” and “only designed for general fitness and wellness purposes.” The problems that optical oximeters have with darker skin is well known, painfully obvious, and a basic reality of physics.

[ashwagary]

I doubt it is "well known" to the billions of darker skinned potential Apple customers.

Going further, the vast majority of retail consumers have no knowledge of technical limitations regardless of skin color.