Another possible moral could be about the power of words and wishes. Since the guy made this strange wish, it shows that our words have power and we should think before we speak, especially when it comes to making wishes. Even if it's a humorous or absurd wish, it still reflects on how we use our language and the ideas we put out there.
It could also be a moral about self - acceptance. Maybe the guy felt he needed to be different in some strange way like having long nipples, but in reality, he should have been happy with himself as he was. So the moral could be to love and accept yourself without desiring such odd changes.
If this is a comical story, the moral might be that we should be careful what we wish for. Just because something seems funny or different to wish for doesn't mean it will have positive consequences.