Then, about half a century ago, came the American huggy movement. Instant intimacy was going to solve everyone's problems by making them feel good, which, in turn, would end war and strife. It took rather vigorous forms among some, but eventually infiltrated even the most staid parts of society, where the handshake had been the greeting that fathers gave their young sons.
I shake hands. I particularly enjoy shaking the hands of people who attempt to greet me with inappropriately wide-open arms. I look people in the eye too and say "How do you do?" or "It's nice to see you."
In school in the 70s and 80s, everyone was quite militant about hugging and it got under my skin. It was the new rigidly adhered-to protocol and regularly flouting it was a quick way to get labeled weird and anti-social. So of course, I had to flout it. It's just a thing.
Oh, and by the way Mrs. Obama, I realise that you are a come-lately upstart and so can have no concept of how civilised people behave, so here's a tip for you,
YOU DON'T TOUCH THE MONARCH!