i understand your point.
i feel like to an extent, lots of things in the world are like this nowadays. when a close friend of mine/classmate passed away at school i kind of felt guilty for not crying. obviously i was torn up on the inside and upset about it, but all around me people were balling their eyes out and hugging one another and the way my emotions come to the surface is just different than that.
now of course i did cry, ALOT, later in the night when it really hit me, but i think it's that initial thought that leads to those posts, kind of like "everybody is posting on the wall, i now feel a moral responsibility to do so otherwise it'll look like i'm not sad about so and so's death."
and that idea carries over to other things, it's sort of like you don't mean something unless you've posted it publicly, you know? and this is somewhat like what happens in movies. in a movie, character A will be miserable about something. the viewers will clearly recognize this because they observe his every action, however, the other characters fail to see it because he does not display them publicly. EXCEPT, in real life, there is no audience, and these feelings or ideas or opinions go completely unnoticed (i believe this happens now partly because friendships and personal connections aren't valued as much as they used to be due to social networking sites)