This is true, by definition. However I'd note that it won't necessarily hurt you, and it will help you if that appendage is useful - gives you any kind of selective advantage.
If something is highly complex so that it is useless unless it is already constructed in one go, such as a light sensitive spot
Oh yes, the old eye canard. Actually, the evolution of the eye is pretty well understood. You might want to google it and save me the trouble of copying and pasting a primer for you.
Copy and paste away, and we'll see how well you do at defending it.