This doesn't mean that you're going to get inundated with meaningless shares. That would be a horrible user experience. In fact, Facebook put a lot of time and effort into making sure that is exactly what didn't happen. It's the very reason why timeline was built. It's why ticker was built. They did this because they want a place for the increased sharing to go, without degrading user experience.
But here's the really exciting part. Once all this data is in the graph, timeline and ticker will pale in comparison to what developers can do with all of this new, structured data. That is the really important thing here.
Implicit sharing is not so that you can get a notification every time someone listens to a song. It's so that a talented young developer can come along and create a beautiful application that visualizes all of your song listens, how it makes you similar or different from your friends.
Don't worry Farhad. Explicit sharing and taste isn't going away. I will still pay more attention to the link you posted of that song you love than the song that blips by in my ticker. I wouldn't criticize the new graph until its matured and we've seen the next generation of amazing apps that are going to be enabled.