The interesting thing about Piecemeal purchases: people tend to think they are spending less while actually spending more. It's exactly the same reason why an eBay seller starts out selling their old Xbox for 50cents with no reserve. Everyone goes "OMG THAT IS SO CHEAP", and bids. When they price exceeds what the Xbox is worth, people still keep bidding, because the process is addictive.
An A La Carte Feature system works on the same principle. Smaller individual charges, larger final revenue.