None of those reasons apply for Ellie.
I have chosen not to because, while it isn't silly, it is putting something "readable" into your dog. I consider it a mini computer and Ellie is not a robot.
So it is more of an ethical reason for me. I see it coming to humans and do not support it at all. I am a person a prefer not to be identified by a chip.
That's all.
I certainly understand why people would want to do it though. It is a personal preference.