Is it? It appears that his AMA was online for maybe 45 minutes. How long should we expect the President of the United States to stay on the site for? Presumably has has other things to do.
1. Space Race
2. Internet Freedom
3. Favorite Basketball Player
4. Small-Business tax breaks
5. First Activity on Nov 7
6. Most Difficult Decision
7. Money in Politics
8. White House Beer Recipe
9. Jobs
10. Work/Life Balance
Also, he brought up Afghanistan on his own in response to the 'hardest decision' question. That's not exactly a fluff answer.
Questions about the state of Iraq, Syria, Libya, Iran, Egypt, et al would have been more interesting. Characterizing sending more troops as a hard decision is not too surprising.
That said, he did come about as close as he could to acknowledging the surge in Afghanistan didn't accomplish much. And he called for a constitutional amendment on Citizen's United, which he apparently hadn't done in public before (according to news outlets trumpeting it).
I also have things to do and manage to fit in at least a couple of hours a day on reddit