FWIW -- and it appears that pg has just implemented exactly this -- I decided to play a game with my "average" a while back, back when it was a reasonable value.

I found that it didn't improve my interaction with the site, it just changed the way that I "played the game". Not literally playing a game, but there was a clear difference in motivations for commenting.

For example: thread is more than 6 hours old? Don't comment, nobody will ever see it or upvote, so my average will get dragged down. Don't reply to any comment at the bottom of a long thread. Use short, witty comments, because those take the least amount of effort for others to upvote (I'm not good at making comments like that, though). Etc.