[salawat]

This is a cop out to be honest.

Just because you can make an airplane that works bereft of the working principles of a bird does not mean that the same fundamental principles of the biological system cannot lead you to further breakthroughs.

In fact, all your analogy really suggests taken to it's logical conclusion is that we shouldn't look at a system already created to solve new problems. You could just as easily say "There is no reason to build a helicopter or hovercraft like a plane." At the end of the day, the same working principles are at work, and there is value to be found in the process by which the essential characteristics of one design are distilled and modified to give birth to another.

A hovercraft can be inspired by a turbofan. A helicopter or or bird can lead one to the conclusion of fixed wing flight, just as the fixed wing can lead you to rotary flight.

In short, it is a shallow person who stops looking because airplanes don't flap.