Most importantly, they appear comfortable simply being together.
That quality can be difficult to reproduce intentionally.
When someone knows a photograph will be seen by a large audience, even a casual pose can become calculated. People may automatically adjust their posture, facial expression, clothing, hair, or body position.
The result may be a beautiful photograph—but it can also feel less spontaneous.
Older photographs often had a different purpose.
A camera might come out during a birthday, a night with friends, a family gathering, a holiday, or an ordinary afternoon.
The photograph existed primarily as a memory.
It did not necessarily need to perform.