According to a recent report from Wall Street Journal, it seems that Apple originally planned for the Apple Watch to have a whole range of exciting health-tracking features. However, it seems they had to cut many of them because of malfunctioning sensors.
The Apple Watch was originally meant to track how stressed you are by measuring the conductivity of skin. It also included an electrocardiogram feature that was capable of measuring a user's heart rate.
But Apple's engineers found out that they couldn't get the health-tracking features to work, as the sensors weren't being accurate with people with hairy arms or dry skin. The Apple Watch didn't work properly either when it was worn too loosely around the wrist. And we all know how much attention Apple pays to detail, so they just had to cut these features.
Apple also planned for blood-pressure and blood-oxygen-level tracking, but these features also won't be present in the first generation of the watch.
The Wall Street Journal also says the Apple Watch was known at Apple by the name "black hole" because it was consuming more and more resources. The publication says that development of the device took over four years.