I agree, it is an "insurance" policy. The warantee company is betting that nothing will fail on the motor, and you are betting that it will. The odds are in the warantee company's favor. You also want to read the fine print very carefully.
Many motors come with long warantees--such as the Suzuki "give me six".
I have a Yahama 115 and it is a great motor. It survived a 50 foot fall during a hurricane, sitting neglected in the open for 7 months awaiting insurance adjustment--and still ran like a top when I started it.