I love local multiplayer but don't have much taste for online gaming. There's no real satisfaction for me in beating someone I don't know, and it irks me when others gloat in winning.
The worst is when an opponent drops out of a game for losing, or maybe the worst is when a teammate blames you for an "error," or maybe the worst is watching opposing teammates tear up each other for what was, essentially, your own talent.
I dunno -- lots of downside for me, and not much upside.
I'm 31 as of this week.