You've all had bad games, but you must have had good games. Where someone on your team is both a strong player and a good teammate. They carry the entire game without complaining, give tips without being overbearing, and in general are just awesome to play with.
Shouldn't these players be rewarded?
I know we have reports to punish people after a game (supposedly, but let's not get into that), so I propose that Riot balances this out with a report to reward people after a game.
A quick MVP poll at the end of the game for each team. A majority vote from your own team (3 other players) gets that player a small IP boost -- and a warm fuzzy feeling for being recognized.
I'd hope that this encourages players to be better to each other, too. Positive reinforcement is far more effective than negative reinforcement