I agree. What you describe is also found in the best hunting dogs. It's that "I'm your best buddy, but let's go out and have some fun" attitude.
Some people hate the sight of Arabs doing dressage, but any breed can do it well. You just need to know the breed in order to judge whether the horse is doing well for that breed. Arabs have all the collected movements down pat, since they can just about roll themselves up in a ball.
I think it's the attitude that makes Arabs great sport horses. There may be no single thing they can do perfectly, but they can do most everything pretty well, and always have fun doing it. Just like with a dog, if you can convice an Arab that he's going to have fun, you'll have no trouble.
Your post got me to thinking about my friend who competed in dressage on her Pony of Americas. He is only about 14hh. None of the warmblood folk though she should be there either, but she had a good time showing him.