"It makes me wonder what would have happened in Janice Joplin had of been born in 1970 and her success depended upon music videos instead of her talent. "

I think Janice would have still been popular. She would most likely have had a devote underground/indie audience first that would have slowly filtered to a less obscure, mainstream audience. She would have sold a good number of units. Much like Jeff Buckley. I believe Janice sold much more records after her death than prior to.

Come to think of it, I don't think I've ever seen a video for aprox. two thirds of  the artists I listen to/buy.