You say that but Force touch Launched in September 2014 . With the current technology they could or have developed a way to be 100% reliable and use very very small battery. So you can't really say that if it was in a brand new iPhone today ? or they could make haptic touch and force touch and switch it off in settings tooForce Touch was too unreliable. Long tap is much more reliable.
Also, when nobody copies you technology, you know it’s a lemon. Nobody copied Force Touch.