the main reason games like Farmville maintain a huge player base is the enticement of the metagame. The actual game mechanic of farming — which comprises most of the game — is unfathomably dull. It’s the abstracted layer above the farming that creates the primary motivation: ribbons (achievements), new items, leaderboards, etc.
But the blur of time-consumption and value is simultaneously damaging Farmville. Because satisfaction is derived only from the metagame, success is a measure of how many hours you’re willing to play, not your abilities. Players who have invested a lot of time into the game end up feeling bitter about the fruits (or vegetables) of their labor.
via sleepoversf.com