While a lot of what is said here is true, people are far less formal today than in the past.
When I was growing up in the 50s my parents would drag out the Kodak Brownie Hawkeye and we would stand there like a stick in front of something and smile. No hugging etc.
These days people have had a lot of pictures taken of themselves especially in some sort of group and they automatically all hug together and look far more fun and relaxed.
I prefer the pictures today much more than the stiffness and embarrassment of yesterday.