@Foofie,
I think we all subscribe to some sort of ceremonials. What we in daily life call well behaving. We say thank you, we open doors, we don´t smoke, we use knife and fork and don´t eat with our fingers etc etc
On international level there has to be a protocol as people from all over the world get together and have different rules about how to behave. Don´t serve pork to Muslims, don´t touch a Japanese and many other things.
The Queen often has to shake hands with hundreds of people in a long row - the protocol says don´t touch her. It is tiring enough to shake hands with maybe hundred people and then having to be hugged by them would be too much. One smells of after shave the next has too much perfume on, the third one smoked a cigar the fourth one smells of garlic......poor woman.
The picture of those two looks cute and the Queen´s reaction was natural, but does this really mean you Americans did teach us Europeans something?
All is showed was that The First Lady brooke the rules of behaviour on the diplomatic carpets. We all fall for it and think it is oh so cute.......
If you were to meet a famous respected person in USA twice your age would you just hug that person or put your arm around him/her? I doubt it.