Second, the "free" everyone is talking about isn't really "free." Whether it is time or gems or coins you must collect, there is a price of admission to continuing these kinds of games. For most, being charged constantly (buy 10 gems, use them, rinse, repeat) for consumable IAP is not the best way to play a game.
These free games prey on a player's impatience, hoping they will spring for some IAP in order to proceed in the game. Is it SO bad to put a price on the game instead?