Apple did not put a camera on the Apple Watch because it was not a necessary or desirable feature for the device at the time of its release.
The Apple Watch is a smartwatch that is designed to be worn on the wrist and to provide quick, convenient access to a variety of features and services. A camera would add additional complexity and bulk to the device, which would detract from its design and portability.
Additionally, a camera on the watch would not provide as good of an experience as using a camera on a phone or other device, due to the limited space and controls on the watch.
For these reasons, Apple decided not to include a camera on the Apple Watch. However, subsequent versions of the Apple Watch may include a camera or other new features based on user feedback and technology advancements.