I can tell you from my admittedly limited mobile social game development experience that user acquisition is really expensive. You need the users you get to make lots of purchases. If your purchases suck, or elicit regret, you're not going survive for very long. It is very common industry advice that purchases should feel really good and provide instant gratification. Industry experts know that once a user makes a first purchase they have a smaller barrier of entry for making more. The industry is all about whales, not about making a quick buck on a user who doesn't know better.

Of course there are companies who don't know any better that are trying to money grab as much as possible, but they're not as successful as you might think. They achieve ranking with a large advertising budget before disappearing into obscurity. But what a lot of people don't want to accept is that a game like FarmVille is a good game that many people legitimately enjoy and feel good spending money on.