What? I never said sunsets weren't beautiful. That's why people share them. I don't think of them as just a social bridge as the previous poster, but I was merely stating that sharing them can be the biggest value seen by others.
Aside from sharing, we like to photograph things as some sort of time-space marker for ourselves, even if we never do anything with it. "This is memorable, so I should take a photo to affirm that." That's why everyone takes a goddamn photo of the Eiffel Tower.