I could easily spend two years painting a smile and it would never, ever be important.
Right. But you are not Davinci, and you are not historically appreciate for your artistic merit.
Everyone who appreciates Davinci understands how tough the Mona Lisa was for him and how it was a personal accomplishment. And so they celebrated it.
It's like clapping when your kid FINALLY paints a body on a person, instead of drawing the legs right out from the bottom of the head. Hahaha