I shoot things, and get loot. Its what they billed to me in every promo and trailer this game has, and I do it whenever I play the game. --- GT: THE Terry May Nothing is more badass than being nice to a lady!
Like the Cracked article mentions towards the end, it only really works because real life sucks and doesn't provide readily tangible rewards, causing people to jump into video games as an escape.
Hell, achievements/trophies are basically another aspect of this approach. They're attempting to put you in competition with other gamers to keep you playing. They might as well be called e-peen points. --- "I'd rather betray the world than let the world betray me." -Cao Cao