Recall the last time that you got good news and wanted to share it with others.
Did you email people? Call them? Post it on Facebook or tweet it?
Now think about how you conveyed good news long ago, when you told people in letters, by calling them at home, or face-to-face.
Compare the two dissemination methods. The internet makes it easier and faster to share news with more people, but the internet also reduces the time for thoughts of "I have good news" in your brain, perhaps reducing the happiness that you feel from that news.
I've found, for example, that I am happier when I keep a nice email in my inbox for longer, before replying or archiving it, compared to immediately hitting reply and moving on, filing away those happy thoughts.
On a more profound level, I can say that the internet puts us into a "one-night stand" cycle of excitement-fulfillment-emptiness that needs constant attention. During the pre-internet era, we were more likely to walk around for days with the same story, telling different people of how happy we were -- a version of enduring romance where you can appreciate and return to the topic, like you would to a lover who stays around.
I'm not sure if we are "hard coded" to feel emotions at pre-internet "wetware" speeds, but I have a feeling. Do you?
Bottom Line: Leave bad news to the internet (get it over with); enjoy good news face-to-face.