Why would any company, especially Apple, use the a battery than can only last 3 hours on, in a watch? As in, the sort of watch that is designed to tell time.
Also, your expectations of Android are very wrong. Yes, Android is known for pretty poor battery efficiency when compared to iOS, but Android Wear devices can last for days, permanently on.
This is not a watch. It is a computer on your wrist. If your compare it to Android Wear you are completely missing the point.