It's all about trying to appear to be more popular than you really are. I don't believe that Obama even writes his own posts and tweets. The guy cannot seem to say anything that sounds good unless he is reading a speech written by someone else off of a teleprompter. He fumbles his way through everything that is not scripted for him.
Hey, here is an idea. Perhaps he should have Biden write witty posts and tweets for him. Biden always says some interesting things.