I agree with the above. I think also that the reason people add hello's and thank you's is because they like to humanize the radio a little bit. That way it doesn't sound like a bunch of robots talking to each other. I was flying over Indy center one day and everybody on the radio was saying Seeya! when they got released to another center. It was like a competition to see who could say it in yet another new and interesting way. It really made the long boring flight more fun for everybody.

A decent pilot can usually sense when the controllers need you to be a concise robot and when you can chill out a little bit and be a human being.

I hope this post will not offend any robots. It's not that you're wrong, it's just that you're not any fun.